Litz wire battery powered device

ABSTRACT

A medical instrument is disclosed. The medical instrument includes a housing and a handle for gripping by a user, an end effector coupled to the handle and having at least one electrical contact, a battery, and a radio frequency (RF) generation circuit coupled to and operated by the battery. The RF generation circuit is operable to generate an RF drive signal and to provide the RF drive signal to the at least one electrical contact, wherein the RF generation circuit is supported by the housing. The RF generation circuit includes a resonant circuit that includes at least one inductive element constructed of litz wire.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/550,768, entitled “MEDICAL INSTRUMENT,” filed onOct. 24, 2011, which is incorporated herein by reference in itsentirety.

This application is related to the following commonly assigned U.S. andPCT International Patent Applications:

U.S. patent application Ser. No. ______, Attorney Docket No.END7074USNP1/110568-1, entitled “BATTERY SHUT-OFF ALGORITHM IN A BATTERYPOWERED DEVICE,” concurrently filed, which is incorporated herein byreference in its entirety.

U.S. patent application Ser. No. ______, Attorney Docket No.END7074USNP2/110568-2, entitled “USER INTERFACE IN A BATTERY POWEREDDEVICE,” concurrently filed, which is incorporated herein by referencein its entirety.

U.S. patent application Ser. No. ______, Attorney Docket No.END7074USNP3/110568-3, entitled “BATTERY INITIALIZATION CLIP,”concurrently filed, which is incorporated herein by reference in itsentirety.

U.S. patent application Ser. No. ______, Attorney Docket No.END7074USNP4/110568-4, entitled “BATTERY DRAIN KILL FEATURE IN A BATTERYPOWERED DEVICE,” concurrently filed, which is incorporated herein byreference in its entirety.

U.S. patent application Ser. No. ______, Attorney Docket No.END7074USNP5/110568-5, entitled “TRIGGER LOCKOUT MECHANISM,”concurrently filed, which is incorporated herein by reference in itsentirety.

PCT International Patent Application Serial No. ______, Attorney DocketNo. END7074WOPCT/110568PCT, entitled “MEDICAL INSTRUMENT,” concurrentlyfiled, which is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates to the field of medical instruments andin particular, although not exclusively, to electrosurgical instruments.The present disclosure also relates to drive circuits and methods fordriving such medical instruments. Additionally, the present disclosureis directed to lockout mechanisms, user interfaces, initializationtechniques, and battery power conservation circuits and methods for suchmedical instruments.

Many surgical procedures require cutting or ligating blood vessels orother internal tissue. Many surgical procedures are performed usingminimally invasive techniques where a handheld instrument is used by thesurgeon to perform the cutting or ligating. Conventional hand-heldelectrosurgical instruments are generally large and bulky and requirelarge power supplies and control electronics that are connected to theinstrument through an electrical supply line.

Conventional corded electrosurgical instruments are large in size, havelarge power supplies and control electronics, and take up a lot of spacein the operating room. Corded electrosurgical instruments areparticularly cumbersome and difficult to use during a surgical procedurein part due to tethering of the hand-held electrosurgical instrument tothe power supply and control electronics and the potential for cordentanglement. Some of these deficiencies have been overcome by providingbattery powered hand-held electrosurgical instruments in which the powerand control electronics are mounted within the instrument itself, suchas within the handle of the instrument, to reduce the size of theelectrosurgical instrument and make such instruments easier to useduring surgical procedures.

Electrosurgical medical instruments generally include an end effectorhaving an electrical contact, a radio frequency (RF) generation circuitfor generating an RF drive signal and to provide the RF drive signal tothe at least one electrical contact where the RF generation circuit alsoincludes a resonant circuit. The RF circuit includes circuitry togenerate a cyclically varying signal, such as a square wave signal, froma direct current (DC) energy source and the resonant circuit isconfigured to receive the cyclically varying signal from the switchingcircuitry. The DC energy source is generally provided by one or morebatteries that can be mounted in a handle portion of the housing of theinstrument, for example.

The design of battery powered hand-held electrosurgical instrumentsrequires the electronics in the power supply and RF amplifier sectionsto have the highest efficiency possible in order to minimize the heatrejected into the relatively small handheld package. Increasedefficiency also improves the storage and operational life of thebattery. Increased efficiency also minimizes the size of the requiredbattery or extends the life of a battery of a given size. Thus, there isa need for battery powered hand-held electrosurgical instruments havinghigher efficiency power supply and RF amplifier sections.

SUMMARY

In one embodiment, a medical instrument includes a housing and a handlefor gripping by a user, an end effector coupled to the handle and havingat least one electrical contact, a battery, and a radio frequency (RF)generation circuit coupled to and operated by the battery. The RF drivecircuit is operable to generate an RF drive signal and to provide the RFdrive signal to the at least one electrical contact. The RF generationcircuit is supported by the housing. The RF generation circuit comprisesa resonant circuit comprising at least one inductive element constructedof litz wire.

FIGURES

FIG. 1 illustrates the form of an electrosurgical medical instrumentthat is designed for minimally invasive medical procedures, according toone embodiment.

FIG. 2 illustrates another view of the electrosurgical medicalinstrument shown in FIG. 1.

FIG. 3 illustrates another view of the electrosurgical medicalinstrument shown in FIG. 1.

FIG. 4 illustrates a sectional view of the electrosurgical medicalinstrument illustrating elements thereof contained within a housing,according to one embodiment.

FIG. 5 illustrates a partial sectional view of the electrosurgicalmedical instrument in a locked out position to prevent the actuation ofthe control lever, according to one embodiment.

FIG. 6 illustrates a partial sectional view of the electrosurgicalmedical instrument in a full stroke position, according to oneembodiment.

FIG. 7 illustrates the electrosurgical medical instrument comprising aninitialization clip interfering with the handle, according to oneembodiment.

FIG. 8 is another view of the electrosurgical medical instrumentcomprising an initialization clip as shown in FIG. 7, according to oneembodiment.

FIG. 9 illustrates a sectional view of a housing portion of anelectrosurgical medical instrument showing an electronic circuit deviceportion of an electronics system, according to one embodiment.

FIG. 10 illustrates a second electronic substrate comprising an inductorand a transformer that form a part of the RF energy circuit, accordingto one embodiment.

FIG. 11 illustrates two separate substrates provided where the digitalcircuit elements are located on a first substrate and the RF amplifiersection and other analog circuit elements are located on a secondsubstrate, according to one embodiment.

FIG. 12 illustrates a partial cutaway view of a housing to show anelectrical contact system, according to one embodiment.

FIG. 13 illustrates a partial cutaway view of a housing to show anelectrical contact system and an inner sheath removed, according to oneembodiment.

FIG. 14 illustrates a partial cutaway view of a housing with anelectrically conductive shaft removed to show an electrical contactelement, according to one embodiment.

FIG. 15 illustrates a partial sectional view of the electrosurgicalmedical instrument in a locked position, according to one embodiment.

FIG. 16 illustrates another partial sectional view of theelectrosurgical medical instrument in a locked position, according toone embodiment.

FIG. 17 illustrates another partial sectional view of theelectrosurgical medical instrument with an activation button partiallydepressed to activate the energy circuit without releasing the knifelockout mechanism, according to one embodiment.

FIG. 18 illustrates another partial sectional view of theelectrosurgical instrument with the activation button fully depressed toactivate the energy circuit and release the knife lockout mechanism,according to one embodiment.

FIG. 19 illustrates another partial sectional view of theelectrosurgical medical instrument with the activation button fullydepressed to activate the energy circuit with the knife lockoutmechanism released and the knife fully thrown, according to oneembodiment.

FIG. 20 is a perspective view of an initialization clip, according toone embodiment.

FIG. 21 is a partial cutaway view of the initialization clip shown inFIG. 20, according to one embodiment.

FIG. 22 illustrates an RF drive and control circuit, according to oneembodiment.

FIG. 23 illustrates a perspective view of one embodiment of atransformer employed in the RF drive circuit illustrated in FIG. 22.

FIG. 24 illustrates a perspective view of one embodiment of a primarycoil of the transformer illustrated in FIG. 23.

FIG. 25 illustrates a perspective view of one embodiment of a secondarycoil of the transformer illustrated in FIG. 23.

FIG. 26 illustrates a bottom view of the primary coil illustrated inFIG. 24.

FIG. 27 illustrates a side view of the primary coil illustrated in FIG.24.

FIG. 28 illustrates a sectional view of the primary coil illustrated inFIG. 24 taken along section 28-28.

FIG. 29 illustrates a bottom view of the secondary coil illustrated inFIG. 25.

FIG. 30 illustrates a side view of the secondary coil illustrated inFIG. 25.

FIG. 31 illustrates a sectional view of the secondary coil illustratedin FIG. 30 taken along section 31-31.

FIG. 32 illustrates a perspective view of an inductor employed in the RFdrive circuit illustrated in FIG. 22.

FIG. 33 illustrates a bottom view of the inductor illustrated in FIG.32.

FIG. 34 illustrates a side view of the inductor illustrated in FIG. 32.

FIG. 35 illustrates a sectional view of the inductor illustrated in FIG.34 taken along section 35-35.

FIG. 36 illustrates main components of a controller, according to oneembodiment.

FIG. 37 is a signal plot illustrating the switching signals applied to afield effect transistor (FET), a sinusoidal signal representing themeasured current or voltage applied to a load, and the timings when asynchronous sampling circuit samples the sensed load voltage and loadcurrent, according to one embodiment.

FIG. 38 illustrates a drive waveform for driving an FET gate drivecircuit, according to one embodiment.

FIG. 39 illustrates a diagram of a digital processing system located ona first substrate, according to one embodiment.

FIG. 40 illustrates a battery discharge circuit, according to oneembodiment.

FIG. 41 illustrates a RF amplifier section with an output sensing testcircuit and magnetic switch element, according to one embodiment.

FIG. 42 illustrates a fused battery connected to a substrate-mountedFET, according to one embodiment.

FIG. 43 illustrates a fused battery connected to a substrate-mountedcontrol relay, according to one embodiment.

FIG. 44 illustrates a potted fused battery connected to asubstrate-mounted FET, according to one embodiment.

FIG. 45 illustrates a potted fused battery connected to asubstrate-mounted control relay, according to one embodiment.

FIG. 46 illustrates a potted fused battery including a reed relay andcontrol FET, according to one embodiment.

FIG. 47 illustrates a potted fused battery including a reed relay andcontrol relay, according to one embodiment.

FIGS. 48A and 48B represent a flow diagram of a process for initializinga medical instrument fitted with an initialization clip, according toone embodiment.

FIGS. 49-57 illustrates the ornamental design for a surgical instrumenthandle assembly as shown and described, according to one embedment,where:

FIG. 49 is a left perspective view of a handle assembly for a surgicalinstrument.

FIG. 50 is a right perspective view thereof.

FIG. 51 is a left perspective view thereof.

FIG. 52 is a left view thereof.

FIG. 53 is a front view thereof.

FIG. 54 is a right view thereof.

FIG. 55 is a rear view thereof.

FIG. 56 is a top view thereof.

FIG. 57 is a bottom view thereof.

DESCRIPTION

Before explaining various embodiments of medical instruments in detail,it should be noted that the illustrative embodiments are not limited inapplication or use to the details of construction and arrangement ofparts illustrated in the accompanying drawings and description. Theillustrative embodiments may be implemented or incorporated in otherembodiments, variations and modifications, and may be practiced orcarried out in various ways. Further, unless otherwise indicated, theterms and expressions employed herein have been chosen for the purposeof describing the illustrative embodiments for the convenience of thereader and are not for the purpose of limitation thereof.

Further, it is understood that any one or more of thefollowing-described embodiments, expressions of embodiments, examples,can be combined with any one or more of the other following-describedembodiments, expressions of embodiments, and examples.

The present disclosure is directed generally to medical instruments andin particular, although not exclusively, to electrosurgical instruments.The present disclosure also is directed to drive circuits and methodsfor driving such medical instruments. Additionally, the presentdisclosure is directed to lockout mechanisms, user interfaces,initialization techniques, and battery power conservation circuits andmethods for such surgical instruments.

For clarity of disclosure, the terms “proximal” and “distal” are definedherein relative to a surgeon grasping the electrosurgical instrument.The term ‘proximal” refers the position of an element closer to thesurgeon and the term “distal” refers to the position of an elementfurther away from the surgeon.

Many surgical procedures require cutting or ligating blood vessels orother vascular tissue. With minimally invasive surgery, surgeons performsurgical operations through a small incision in the patient's body. As aresult of the limited space, surgeons often have difficulty controllingbleeding by clamping and/or tying-off transected blood vessels. Byutilizing electrosurgical forceps, a surgeon can cauterize,coagulate/desiccate, and/or simply reduce or slow bleeding bycontrolling the electrosurgical energy applied through jaw members ofthe electrosurgical forceps, otherwise referred to as clamp arms.

FIG. 1 illustrates the form of an electrosurgical medical instrument 100that is designed for minimally invasive medical procedures, according toone embodiment. As shown, the instrument 100 is a self contained device,having an elongate shaft 102 that has a housing 112 with a handle 104connected to the proximal end of the shaft 102 and an end effector 106connected to the distal end of the shaft 102. In this embodiment, theend effector 106 comprises medical forceps 108 having a movable jawmember and a cutting blade or knife (not shown) coupled to an innersheath (not shown) located within the shaft 102 that are controlled bythe user manipulating a control lever 110 (e.g., hand trigger) portionof the handle 104. In the illustrated embodiment, the control lever 110(e.g., hand trigger) is in the form of a hook (e.g., shepherd's hook)having a curved front portion and a rear portion where the rear portionextends below the front portion. The curved front portion and the rearportion define an aperture therebetween to receive the user's hand tooperate the control lever 110. During a surgical procedure, the shaft102 is inserted through a trocar to gain access to the patient'sinterior and the operating site.

The surgeon will manipulate the forceps 108 using the handle 104, thecontrol lever 110, and rotation knob 116 until the forceps 108 arelocated around the vessel to be cauterized. The rotation knob 116 iscoupled to the shaft 102 and the end effector 106. Rotation of therotation knob 116 causes rotation of the shaft 102 and the end effector106. In one embodiment, the shaft 102 is continuously rotatable greaterthan 360° using the rotation knob 116. To perform the desiredcauterization Electrical energy at an RF frequency (it has been foundthat frequencies above about 50 kHz (e.g., ˜100 kHz and higher) do notaffect the human nervous system) is then applied by, in a controlledmanner, to the forceps 108 by actuating an activation button 114. Theactivation button 114 has a partial activation position and a fullactivation position.

As shown in FIG. 1, in this embodiment, the handle 104 houses batteriesand the housing houses control electronics for generating andcontrolling the electrical energy required to perform the cauterization.In this way, the instrument 100 is self contained in the sense that itdoes not need a separate control box and supply wire to provide theelectrical energy to the forceps 108. The instrument 100 also comprisesa first visual feedback element 118 a on the proximal end of the housing112 to indicate that the device is ready for use and functioningnormally, that there are a limited number of transections remaining,that RF energy is being delivered, that an alert condition or faultexists, that the initialization clip was removed, among otherindications. In one embodiment, the first visual feedback element 118 ais a light emitting diode (LED), without limitation. In one embodiment,the first visual feedback element 118 a is a tri-color LED. In oneembodiment, the instrument 100 comprises an integral generator and anon-reusable battery.

FIG. 2 illustrates another view of the electrosurgical medicalinstrument 100 shown in FIG. 1. In one embodiment, the instrument 100comprises a second visual feedback element 118 b located on the proximalend of the housing 112. In one embodiment, the second visual feedbackelement 118 b performs the same function as the first visual feedbackelement 118 a. In one embodiment, the second visual feedback element 118b is an LED, without limitation. In one embodiment, the second visualfeedback element 118 b is a tri-color LED.

FIG. 3 illustrates another view of the electrosurgical medicalinstrument 100 shown in FIG. 1. In one embodiment, the instrument 100comprises a disposal button 120 located on the bottom of the handle 104,for example. The disposal button 120 is used to deactivate theinstrument 100. In one embodiment, the instrument 100 may be deactivatedby pushing and holding the disposal button 120 for a predeterminedperiod. For example, the instrument 100 may be deactivated by pushingand holding the disposal button 120 for about four seconds. In oneembodiment, the instrument 100 will automatically deactivate after apredetermined period. For example, the instrument 100 will automaticallydeactivate either eight or 10 hours after completion of the first cycle.An aperture 115 formed in the handle 104 provides a path for audio wavesor a means for sound generated by an audio feedback element such as apiezoelectric buzzer to escape, for example, from within the handle 104.In one embodiment, the piezoelectric buzzer operates at 65 dBa at onemeter at a frequency between about 2.605 kHz to 2.800 kHz, for example.The aperture 115 enables the sound to escape the handle 104 so that itis comfortably audible to the surgeon while operating the medicalinstrument 100.

FIG. 4 illustrates a sectional view of the electrosurgical medicalinstrument 100 illustrating elements thereof contained within thehousing 112, according to one embodiment. In one embodiment, theinstrument 100 comprises a knife lockout mechanism 200 to prevent theadvancement of an inner sheath 202, which is coupled to a blade (notshown) portion of the medical forceps 108. In the illustratedembodiments, the medical forceps 108 having a movable jaw member that ispivotally movable to clamp down on a vessel when the control lever 110is squeezed proximally in the direction of arrow 122. The cutting bladeor knife (not shown) portion of the medical forceps 108 also advancesdistally when the control lever 110 is squeezed proximally. The cuttingblade, sometime referred to as the knife, is for cutting the vesselafter it has been cauterized. To prevent a “cold cut” of the vessel,which is defined as cutting with no application of energy to the vessel,a knife lockout mechanism 200 prevents the control lever 110 from beingsqueezed and thus prevents the blade from being advanced until theactivation button 114 is fully engaged and a suitable amount of RFenergy is applied to the vessel to properly cauterize it.

The knife lockout mechanism 200 ensures that the activation button 114is fully depressed to activate the RF energy source such that energy isdelivered to the vessel prior to cutting. When the activation button 114is fully engaged, the knife lockout mechanism 200 enables the controllever 110 to be squeezed proximally in the direction of arrow 122. Thisaction advances the inner sheath 202 distally to close the jaw membersof the electrosurgical forceps 108 while the cutting blade issimultaneously advanced to cut the vessel after it is fully cauterized.Therefore, electrosurgical energy is applied to the vessel through thejaw members of the electrosurgical forceps 108 before the cutting bladeadvances.

Also shown in FIG. 4 is an integral energy source 300, according to oneembodiment. In the embodiment illustrated in FIG. 4, the integral energysource 300 may be a non-replaceable DC energy source such as a battery300 that fits within the handle portion 104 of the housing 112. Oneembodiment of the energy source 300 is described in more detailhereinbelow.

In one embodiment, the battery 300 is a 1000 mAh, triple-cell LithiumIon Polymer battery, Lithium battery, among others. The battery 300 willbe fully charged prior to Ethylene Oxide (EtO) sterilization, and willhave a fully charged voltage of about 12V to about 12.6V. The battery300 will have two 20 A fuses fitted to the substrate which connects thecells, one in line with each terminal. In other embodiments, the batterycapacity may be greater than 1000 mAh, such as, up to about 3000 mAh,for example.

In one embodiment, the minimum distance between terminals of the battery300 may be about 3 mm such that sparking conditions require anatmosphere with a dielectric breakdown of ≦4200V/m. Even at the lowestpressures encountered in an EtO cycle, for a condition of pure EtO,across a 3 mm gap the breakdown voltage is approximately 450V. This ismore than an order of magnitude greater than the maximum batteryvoltage, and this is further mitigated by the use of a Nitrogen blanketduring the sterilization process.

Also shown in FIG. 4 is an electronics system 400, according to oneembodiment. In one embodiment, the electronics system 400 comprises anRF generation circuit to generate an RF drive signal and to provide theRF drive signal to the at least one electrical contact where the RFgeneration circuit also includes a resonant circuit. The electronicssystem 400 also comprises control elements such as one or more than onemicroprocessor (or micro-controller) and additional digital electronicelements to control the logical operation of the instrument 100. Oneembodiment of the electronics system 400 is described hereinbelow. Theelectronics system 400 including the RF generation circuit is supportedby the housing 112. In one embodiment, RF generation circuit to generatean RF drive signal is integral to the housing 112 and the battery 300 isnon-reusable.

Also referenced in FIG. 4 is a logical lockout mechanism 500, inaccordance with one embodiment. The logical lockout mechanism works incooperation with an initialization clip 600 (see FIGS. 7-9) and 650 (seeFIGS. 20-21) to prevent operation of the instrument 100 until it isremoved. One embodiment of the logical lockout mechanism 500 isdescribed hereinbelow.

FIG. 5 illustrates the electrosurgical medical instrument 100 in alocked out position to prevent the actuation of the control lever 110,according to one embodiment. The control lever 110 comprises a triggerlever 212 portion that is configured to rotate about a trigger pivot 214when the control lever 110 is squeezed in the direction of arrow 122(FIG. 4), unless the instrument is in locked out mode.

In the locked out mode, the trigger lever 212 portion of the controllever 110 is prevented from rotating about the trigger pivot 214 becausea projection 218 of the trigger lever 212 engages a top surface 216 ofan activation button lever 234 that rotates about activation buttonpivot 232 when the activation button 114 is squeezed in the direction ofarrow 220. A contact button torsion spring 224 keeps the activationbutton 114 in an outwardly position to disable the electrosurgicalenergy from being applied while simultaneously engaging the projection218 of the trigger lever 212 with the top surface 216 to lockout theinstrument 100 until the activation button 114 is fully engaged in thedirection of arrow 220.

A second trigger lever 210 comprises a first end that defines a pin slot206 and a second end that defines a tab 226. The pin slot 206 engages apin 208 portion of the trigger lever 212. As the trigger lever 212rotates in the direction of arrow 236 about trigger pivot 214 the pin208 moves within the pin slot 206 to apply a rotation movement to thesecond trigger lever 210. The tab 226 engages an aperture 228 tomechanically couple the second trigger lever 210 to the inner sheath202. Thus, as the trigger lever 212 moves in the direction of arrow 236,the second trigger lever 210 rotates about lever pivot 204 to apply alinear translation motion to the inner sheath 202 in the direction ofarrow 238. A trigger torsion spring 222 engages the second trigger lever210 at a notch 240 formed on the second trigger lever 210. The triggertorsion spring 222 torque balances the hand force applied to the secondtrigger lever 210 through the control lever 110 about the trigger pivot214.

FIG. 6 illustrates the electrosurgical medical instrument 100 in a fullstroke position, according to one embodiment. In order to release thelockout mechanism 200, the activation button 114 is fully engaged in thedirection of arrow 220 to cause the activation button lever 234 torotate about activation button pivot 232 and release the top surface 216from engaging the projection 218. This allows the projection 218 toslidably rotate past a surface 230 of the activation button lever 234 asthe trigger lever 212 slidably rotates in the direction of arrow 236about trigger pivot 214 as the control lever 110 is squeezed, oractuated, proximally by the surgeon. During the control lever 110actuation period, the pin 208 is engaged by the pin slot 206 slidablymoving therein and rotating the second trigger lever 210 about the leverpivot 204. As shown in FIG. 6, in the full stroke position, the innersheath 202 is fully advanced in the distal direction in accordance withthe translation motion applied by the tab 26 and aperture 228 as thesecond trigger lever 210 is fully rotated about the lever pivot 204.Also of note, the trigger and contact button torsion springs 222, 224,respectively, are torqued in order to return the control lever 110 andcontact button 114, respectively, to their normal locked out deactivatedpositions.

FIG. 7 illustrates the electrosurgical medical instrument 100 comprisingan initialization clip 600, according to one embodiment. The clip 600prevents firing the medical instrument 100 without enabling and alsoprovides some protection during shipment. The initialization clip 600 isapplied to the instrument 100 after initialization at the factory andstays on the instrument 100 during storage. Upon removal of the clip600, the instrument 100 is enabled. In one embodiment, if the instrument100 has completed one full energy activation cycle (described in moredetail hereinbelow) and the clip 600 is re-installed, the instrument 100will not function upon removal of the clip 600 a second time.

In addition to the clip 600, other techniques for activating the battery300 are contemplated by the present disclosure. In one embodiment,described but not shown, a “Pull Tab” may be employed to activate thebattery 300. In one embodiment, the Pull Tab may comprise a plasticstrip that physically separates the battery contacts acting as aninsulator. A multi-stage version of this embodiment enables productiontesting.

In another embodiment, described but not shown, a breakaway plastic tabmay be employed to activate the battery 300. In one embodiment, thebreakaway plastic tab separates the battery 300 contacts and cannot bereplaced.

In another embodiment, described but not shown, a mechanical mechanismmay be employed to activate the battery 300. In one embodiment, themechanical mechanism may be activated from outside the battery 300 toopen the battery 300 contacts via a mechanical means.

In another embodiment, described but not shown, a removable battery isprovided, where the battery is removed prior to the sterilizing themedical instrument 100. The removable battery may be sterilized using aseparate sterilization method. For example, the medical instrument 100may be sterilized by EtO and the battery by H₂O₂ (hydrogen peroxide),e-beam sterilization, or any suitable sterilization technique that isnon-destructive to the battery.

In another embodiment, described but not shown, a Hall-effect device maybe employed as an activation means. The Hall-effect device is responsiveto a magnetic field and can be used to detect the presence or absence ofa magnetic field.

In yet another embodiment, a remotely activated switch element 606 (suchas a reed relay, Hall-effect sensor, RF device, optical element, forexample, see FIGS. 8, 10, 41) that disables the electronics system 400when a remote switch activation element 602 (such as, for example, amagnet as shown in FIG. 8, RF device, optical element) is brought intoproximity to the magnetically operated element 606. This particularembodiment is described in more detail hereinbelow in connection withFIGS. 8, 10, 41, and 42-47, for example.

Also shown in FIG. 7 is the activation button 114 in multiple positions.In one embodiment, the activation button 114 is movable over multipleactuation positions to control multiple functions. In the embodimentillustrated in FIG. 7, the activation button 114 is shown in threeseparate positions 114 a, 114 b, 114 c, where in a first position 114 athe activation button 114 is full extended distally outwardly and doesnot result in energizing the RF energy circuit. In a second position 114b the activation button 114 is in a partial depression mode and in athird position 114 c the activation button 114 is in a full depressionmode. During normal operation, e.g., when the clip 600 is removed, whenthe activation button is in the first position 114 a, the lockoutmechanism is engaged and the operation of the control lever 110 isinhibited as previously described in connection with FIGS. 4-6 and theenergy source 300 (FIG. 4) is disconnected from the electronics system400 (FIG. 4). When the activation switch 114 is partially depressed inthe second position 114 b, the device is still mechanically locked outto inhibit the operation of the control lever 110, as previouslydescribed in connection with FIGS. 4-6, but the circuit is connected tothe energy source 300 and becomes partially functional. For example, inone embodiment, several logic functions may be enabled while keeping theRF energy activation circuit disabled. When the activation switch 114 isfully depressed in the third position 114 c, the device is mechanicallyunlocked and enables the operation of the control lever 110, aspreviously described in connection with FIGS. 4-6, but the circuit isconnected to the energy source 300 and becomes fully functional,including enabling the operation of the logic and the RF energy circuit.It will be appreciated, however, that in the configuration of theinstrument 100 shown in FIG. 7, the clip 600 mechanically prevents theoperation of the control lever 110 and also inhibits the operation ofthe electronics system 400 by electrically disconnecting the energysource 300 from the electronics system 400. The functionality of themulti-position activation button 114 as it relates to the mechanical andelectrical lockout will be described in more detail hereinbelow.

FIG. 8 is another view of the electrosurgical medical instrument 100comprising an initialization clip 600 as shown in FIG. 7, according toone embodiment. In FIG. 7, the clip 600 is shown without a cover plateto show the internal structure of the clip 600. As shown in FIG. 8, theclip 600 defines an internal cavity that contains a magnet 602. Themagnetic flux generated by the magnet 602 acts on a magneticallyoperated element 606 located on the electronics system 400. Themagnetically operated element 606 is coupled to the electronics system400 and the energy source 300 and acts as a switch to disconnect andconnect the energy source to the electronics system 400.

In the embodiment illustrated in FIG. 8, the magnetic flux generated bythe magnet 602 causes the magnetically operated element 606 toelectrically disconnect the energy source 300 from the electronicssystem 400, including a transformer 404 and an inductor 406. When themagnet 602 is removed, by removing the clip 600 from the instrument 100,for example, the magnetically operated element 606 electrically connectsthe energy source 300 to the electronics system 400. Accordingly, aslong as the clip 600 with the magnet 602 is located on the instrument100, the instrument 100 is mechanically and electrically locked out. Aspreviously described, when the clip 600 is located on the instrument100, depressing the 114 in the first position 114 a, second position 114b, or third position 114 c does not activate the electronics system 400because the magnetically operated element 606 electrically disconnectsor decouples the energy source 300 from the electronics system 400. Inone embodiment, the magnetically operated element 606 may be a reedswitch, a hall-effect sensor, or any other switch type device that canbe activated by a magnetic field. Still, in another embodiment, themedical instrument 100 may comprise an accelerometer to detect motion.When the accelerometer is at rest, indicating that the medicalinstrument 100 is at rest, the instrument 100 is completely powered downby disconnecting the battery 300 from the electronics system 400. Whenthe accelerometer detects motion, indicating that the medical instrument100 is no longer at rest, the instrument is powered up by connecting thebattery 300 to the electronic system 400.

While undergoing sterilization, the electronics system 400 will not bepowered and will draw only a leakage current of about 1 μA. Theelectronics system 400 may be disabled by the magnetically operatedelement 606 (e.g., a reed switch) and magnet 602 which is encased in theclip 600. The clip 600 is fitted to the medical instrument 100 as partof the manufacturing process, and must be removed to enable power fromthe battery 300. When powered, in the idle condition the load circuitdraws an average of 10 mA, with peaks of up to 65 mA. When theactivation button 114 is pressed, the device draws an average of 5 A,with peaks of 15.5 A from the battery 300. When packaged, the jaws areclosed and there is no material between them. In one non-limitingembodiment, the voltage generated across the jaws is a maximum of 85Vrms. This arrangement means there are two methods for preventing thegeneration of high voltages or currents—the magnetic clip 600 is theprimary disabling mechanism, and the activation button 114 is thesecond. Several connection options for the battery 300 are describedhereinbelow with reference to FIGS. 42-47.

Mechanical fastening elements 604 and 608 are used to hold the clip 600coupled to the medical instrument 100. In the embodiment illustrated inFIG. 8, the clip comprises a first half 612 a and a second 612 b thatcan be fastened using mechanical fastening elements to form aninterference fit, press fit, or friction fit, such that friction holdsthe two halves 612 a, b after they are pushed or compressed together. Inother embodiments, other fastening techniques may be employed to fastenthe two halves 612 a, b such as by ultrasonic welding, snap fitting,gluing, screwing, riveting, among others. Another embodiment of aninitialization clip 650 is described below in connection with FIGS. 20and 21.

FIG. 9 illustrates a sectional view of the housing 112 portion of theelectrosurgical medical instrument 100 showing an electronic circuitdevice 402 portion of the electronics system 400, according to oneembodiment. In one embodiment, the electronic circuit device 402 can beconfigured as a data gathering/programming interface, for example. Inone embodiment, the electronic circuit device 402 can be programmed by aprogramming device (not shown). The electronic circuit device 402 canoutput real-time data such as tissue voltage, current, and impedance toan external data recording device (not shown). In one embodiment, theelectronic circuit device 402 is a non-volatile memory device that canstore computer program instructions and/or tissue voltage, current, andimpedance data.

In one embodiment, the data transfer/device programming function can beimplemented by a connector provided on the housing 112 to couple anexternal data transfer/device programmer device to the electroniccircuit device 402. The external data transfer/device programmer devicemay be employed for two-way communication with the electronic circuitdevice 402. To upload a new program to the medical instrument 100, forexample, the external data transfer/device programmer device can beplugged into the connector to couple to the electronic circuit device402 and then upload the program. Data stored in the electronic circuitdevice 402 could be read just as easily via the connector. The data mayinclude, for example, voltage (V), current (I), impedance (Z), deviceparameters, among others, without limitation.

In one embodiment, the data transfer/device programming function can beimplemented via at least one of the LED 118 a, b interfaces. Forexample, either through the tri-color LEDs 118 a, b or the addition ofan infrared (IR) LED (not shown), an optical data interface can beimplemented. The optical data interface can be employed to transfer datato and from the instrument 100 and/or program the instrument 100. In oneembodiment, a separate hood (not shown) comprising a cavity to receivethe proximal end of the housing 112 comprising the LEDs 118 a, b may beprovided. The hood also comprises optical elements (e.g., IR LEDs)configured for optical communication in order to communicate via theoptical interface comprised of LEDs 118 a, b. In operation, the hood maybe slidably inserted over the proximal end of the housing 112 such thatthe LEDs 118 a, b are optically aligned with the optical elementslocated inside the hood.

FIGS. 10 and 11 illustrate the electrosurgical medical instrument 100without the housing 112 portion to reveal the internal components of theinstrument 100, according to one embodiment. The electronics system 400comprises both digital and RF analog circuit elements. Accordingly, asshown in FIG. 11, two separate substrates 408 a and 408 b are providedwhere the digital circuit elements are located on a first substrate 408a and the RF amplifier section and other analog circuit elements arelocated on a second substrate 408 b. The first and second substrates 408a, b are interconnected by a interconnect device 412. Still in FIG. 11,the first substrate 408 a also includes digital circuit componentsincluding, for example, the electronic circuit device 402 for storingprogram and tissue information. The first substrate 408 a also includesan audio feedback element 410. In one embodiment, the audio feedbackelement 410 is a piezo device. In other embodiments, however, differenttypes of audio feedback devices may be employed without limitation. Itwill be appreciated that in various embodiments, the first and secondsubstrates 408 a, b are formed of printed circuit boards. In otherembodiments, however, these substrates can be formed of any suitablematerials, such as alumina ceramics, for example. The substrates 408 a,b may comprise discrete, integrated, and/or hybrid circuit elements andcombinations thereof. With reference now to FIG. 10, the secondelectronic substrate 408 b comprises an inductor 404 and a transformer406 that form a part of the RF energy circuit. With reference now to theembodiments disclosed in FIGS. 10 and 11, also shown are the dualtri-color LEDs 118 a, b. Also shown is the electrical contact system 700that couple RF energy produced by the RF energy circuits on the secondsubstrate 408 b to the medical forceps 108 (FIGS. 1 and 2). Anelectrical conductor 702 is coupled to the electrical contact system700. The other end of the electrical conductor 702 is coupled to the RFenergy circuit.

FIGS. 12-14 illustrate various views of the electrical contact system700, according to one embodiment. FIG. 12 illustrates a partial cutawayview of the housing 112 to show the electrical contact system 700,according to one embodiment. The electrical contact system 700 comprisesan electrically conductive shaft 716 that is rotatable over 360° andcomprises first and second rotatable electrodes 706, 708. The rotatableelectrodes 706, 708 are electrically coupled to corresponding first andsecond electrical contact elements 704 a, 704 b where the electricalcontact elements 704 a, b are electrically coupled to the electricalconductor 702 (FIGS. 10-11) coupled to the RF energy circuit. Each thefirst and second electrical contact elements 704 a, 704 b comprise firstand second electrical contact points 710 a, 710 b and 712 a, 712 b. Theelectrical contact points 710 a and 712 a are electrically coupled to aside wall 718 of the first rotatable electrode 706 and the electricalcontact points 710 b and 712 b are electrically coupled to a side wall720 of the second rotatable electrode 708. In one embodiment, the twoelectrical contact elements 704 a, b provide four contact points 710 a,712 a, 710 b, 712 b for redundancy. The electrical contact elements 704a, b and corresponding four contact points 710 a, 712 a, 710 b, 712 ballow the rotatable electrodes 706, 708 of the electrically conductiveshaft 716 to rotate over 360°. The two electrical contact elements 704a, b may be formed of any suitable electrically conductive element suchas copper, aluminum, gold, silver, iron, and any alloy including atleast one of these element, without limitation. In one embodiment, thetwo electrical contact elements 704 a, b are formed of beryllium copper(BeCu) and are gold plated for corrosion resistance and good electricalcontact properties. In FIG. 12 the inner sheath 202 is shown slidablyinserted within the electrically conductive shaft 716.

FIG. 13 illustrates a partial cutaway view of the housing 112 to showthe electrical contact system 700 and the inner sheath 202 removed,according to one embodiment. FIG. 13, also shows an electrical element714 that is electrically coupled to the electrical conductor 702 (FIGS.10-11) coupled to the RF energy circuit. The electrical element 714 iscoupled to the electrical contact elements 704 a, b. Accordingly, the RFenergy circuit is coupled to the electrical contact element 704 a, b.

FIG. 14 illustrates a partial cutaway view of the housing 112 with theelectrically conductive shaft 716 removed to show the electrical contactelement 714, according to one embodiment. As shown in FIG. 14, theelectrical contact element 714 is located in a partial circular wall 724that separates the circular cavities 722, 726 configured to rotatablyreceive the respective rotatable electrodes 706, 708 (FIGS. 12-13). Theelectrical contact element 714 is electrically coupled to the twoelectrical contact elements 704 a, b. As shown, the two electricalcontact elements 704 a, b are located on top of the electrical contactelement 714.

FIG. 15 illustrates a partial sectional view of the electrosurgicalmedical instrument 100 in a locked position, according to oneembodiment. FIG. 15 illustrates the electrosurgical medical instrument100 in a locked out position to prevent the actuation of the controllever 110, according to one embodiment. The control lever 110 comprisesa trigger lever 212 portion that is configured to rotate about a triggerpivot 214 when the control lever 110 is squeezed in the direction ofarrow 122 (FIG. 4), unless the instrument is in locked out mode.

In the locked out mode, the trigger lever 212 portion of the controllever 110 is prevented from rotating about the trigger pivot 214 becausea projection 218 of the trigger lever 212 engages a top surface 216 ofan activation button lever 234 that rotates about activation buttonpivot 232 when the activation button 114 is squeezed in the direction ofarrow 220. A contact button torsion spring 224 keeps the activationbutton 114 in an outwardly position to disable the electrosurgicalenergy from being applied while simultaneously engaging the projection218 of the trigger lever 212 with the top surface 216 to lockout theinstrument 100 until the activation button 114 is fully engaged in thedirection of arrow 220.

A second trigger lever 210 comprises a first end that defines a pin slot206 and a second end that defines a tab 226. The pin slot 206 engages apin 208 portion of the trigger lever 212. As the trigger lever 212rotates in the direction of arrow 236 about trigger pivot 214 the pin208 moves within the pin slot 206 to apply a rotation movement to thesecond trigger lever 210. The tab 226 engages an aperture 228 tomechanically couple the second lever to the inner sheath 202. Thus, asthe trigger lever 212 moves in the direction of arrow 236, the secondtrigger lever 210 rotates about lever pivot 204 to apply a lineartranslation motion to the inner sheath 202 in the direction of arrow238. A trigger torsion spring 222 engages the second trigger lever 210at a notch 240 formed on the second trigger lever 210. The triggertorsion spring 222 torque balances the hand force applied to the secondtrigger lever 210 through the control lever 110 about the trigger pivot214.

FIG. 16 illustrates another partial sectional view of theelectrosurgical medical instrument 100 in a locked position, accordingto one embodiment. In the locked position, the knife lockout mechanism200 prevents the control lever 110 from rotating about the trigger pivot214 when the projection 218 of the trigger lever 212 engages a topsurface 216 of the activation button lever 234. The activation buttonlever 234 rotates about the activation button pivot 232 when theactivation button 114 is squeezed or depressed in the direction of arrow220. The activation button 114 is supported independently from theactivation button pivot 232 by a mechanism 254 such that the activationbutton 114 is independently operable from the actuation of the controllever 110 actuate the cutting blade (knife). Thus, the activation button114 can be depressed to energize the instrument 100 without actuatingthe cutting blade (knife). When the activation button 114 is squeezed ordepressed in the direction of arrow 220, the activation button 114actuates a switch 250, which enables energy actuation of the instrument100. Thus, electrosurgical RF energy is applied through jaw members ofthe electrosurgical forceps, otherwise referred to as clamp arms of theinstrument 100. The cutting blade, however, is still locked out by theknife lockout mechanism 200. A tang 252 prevents the activation button114 from being removed by pulling forward on it.

FIG. 17 illustrates another partial sectional view of theelectrosurgical medical instrument 100 with the activation button 114partially depressed to activate the energy circuit without releasing theknife lockout mechanism 200, according to one embodiment. Although theactivation button 114 is partially depressed to actuate the switch 250and energize the instrument 100, but the knife lockout mechanism 200 isstill engaged to prevent the knife from being actuated by the controllever 110. As shown, the projection 218 of the trigger lever 212 isstill engaged with the top surface 216 of the activation button lever234 to prevent the trigger lever 212 from rotating about the triggerpivot 214 when the control lever 110 is squeezed.

FIG. 18 illustrates another partial sectional view of theelectrosurgical instrument 100 with the activation button 114 fullydepressed to activate the energy circuit and release the knife lockoutmechanism 200, according to one embodiment. The activation button 114 isfully depressed to actuate the switch 250 and energize the instrument100 and also releasing the knife lockout mechanism 200. In the fullydepressed mode, the activation button 114 rests on a pin 256. As shown,the projection 218 of the trigger lever 212 is disengaged from the topsurface 216 of the activation button lever 234 that rotates aboutactivation button pivot 232 to enable the trigger lever 212 to rotateabout the trigger pivot 214 when the control lever 110 is squeezed tothrow the knife. As shown, the inner sheath 202 can now be advanced inthe direction indicated by the direction of arrow 238.

FIG. 19 illustrates another partial sectional view of theelectrosurgical medical instrument 100 with the activation button 114fully depressed to activate the energy circuit with the knife lockoutmechanism 200 released and the knife fully thrown, according to oneembodiment. As shown, the inner sheath 202 has advanced in the directionindicated by the direction of arrow 238.

FIG. 20 is a perspective view of an initialization clip 650, accordingto one embodiment. The initialization clip 650 is similar to theinitialization clip 600 described in connection with FIGS. 7-9. FIG. 21is partial cutaway view of the initialization clip 650 shown in FIG. 20,according to one embodiment. With reference to FIGS. 20 and 21, theinitialization clip 650 is attached to the electrosurgical medicalinstrument 100 to prevent firing the medical instrument 100 withoutenabling and also provides some protection during shipment. Theinitialization clip 650 is applied to the instrument 100 afterinitialization at the factory and stays on the instrument 100 duringstorage. Upon removal of the clip 650, the instrument 100 activates inthe manner described with respect to the initialization clip 600 ofFIGS. 6-9. In one embodiment, if the instrument 100 has completed onefull energy activation cycle (described in more detail hereinbelow) andthe clip 650 is re-installed, the instrument 100 will not function uponremoval of the clip 650 a second time. The initialization clip 650comprises a snap button 652 to secure the clip 650 to the instrument 100and a tilted magnetic pocket 654. The magnetic pocket 654 contains amagnet that works in conjunction with a reed switch, or other suitablesensing element, to detect the presence of the initialization clip 650,and thus determine whether it is attached or removed from the instrument100. In other respects, the initialization clip 650 operates similarlyto the initialization clip 600 described in connection with FIGS. 7-9.

The description now turns to the RF drive and control circuitry sectionsof the battery powered electrosurgical instrument 100, according to oneembodiment. As described in FIGS. 10-11, the RF drive and controlcircuitry sections of the electronics system 400 are located on a secondsubstrate 408 b. The electronics elements of the power supply and RFamplifier sections should be designed to have the highest efficiencypossible in order to minimize the heat rejected into the relativelysmall handheld housing 112. Efficiency also provides the longest storageand operational battery life possible. As described in the embodimentsillustrated in FIGS. 23-35, litz wire may be wound around a bobbin coreto reduce AC losses due to high frequency RF. The litz wire constructionprovides greater efficiency and thus also prevents heat generation inthe device.

In various embodiments, efficiency of the power supply and RF drive andcontrol circuitry sections also may minimize the size of the battery 300required to fulfill the mission life, or to extend the mission life fora given size battery 300. In one embodiment, the battery 300 provides alow source impedance at a terminal voltage of 12.6V (unloaded) and a1030 mA-Hour capacity. Under load, the battery voltage is a nominal11.1V, for example.

Radio frequency drive amplifier topologies may vary according to variousembodiments. In one embodiment, for example, a series resonant approachmay be employed where the operating frequency is varied to change theoutput voltage to force the medical instrument 100 to operate accordingto a pre-programmed load curve. In a series resonant approach, theimpedance of a series resonant network is at a minimum at the resonantfrequency, because the reactance of the capacitive and inductiveelements cancel, leaving a small real resistance. The voltage maximumfor a series resonant circuit also occurs at the resonant frequency (andalso depends upon the circuit Q). Accordingly, to produce a high voltageon the output, the series resonant circuit should operate closer to theresonant frequency, which increases the current draw from the DC supply(e.g., battery 300) to feed the RF amplifier section with the requiredcurrent. Although the series resonant approach may be referred to as aresonant mode boost converter, in reality, the design is rarely operatedat the resonant frequency, because that is the point of maximum voltage.The benefit of a resonant mode topology is that if it is operated veryclose to the resonant frequency, the switching field effect transistors(FETs) can be switched “ON” or “OFF” at either a voltage or current zerocrossing, which dissipates the least amount of power in the switchingFETs as is possible.

Another feature of the RF drive and control circuitry section accordingto one embodiment, provides a relatively high turns ratio transformerwhich steps up the output voltage to about 85VRMS from the nominalbattery 300 voltage of about 11.1V. This provides a more compactimplementation because only one transformer and one other inductor arerequired. In such a circuit, high currents are necessary on thetransformer primary to create the desired output voltage or current.Such device, however, cannot be operated at the resonant frequencybecause allowances are made to take into account for the battery voltagedropping as it is expended. Accordingly, some headroom is provided tomaintain the output voltage at the required level. A more detaileddescription of a series resonant approach is provided in commonlyassigned international PCT Patent Application No. PCT/GB2011/000778,titled “Medical Device,” filed May 20, 2011, the disclosure of which isincorporated herein by reference in its entirety.

According to another embodiment, an RF instrument topology comprising anovel and unique architecture is provided for a handheld battery poweredRF based generator for the electrosurgical medical instrument 100.Accordingly, in one embodiment, the present disclosure provides an RFinstrument topology with an architecture configured such that each powersection of the device operate at maximum efficiency regardless of theload resistance presented by the tissue or what voltage, current, orpower level is commanded by the controller. In one embodiment, this maybe implemented by employing the most efficient modalities of energytransformation presently known and by minimizing the component size toprovide a small and light weight electronics package to fit within thehousing 112, for example.

In one embodiment, the RF power electronics section of the electronicssystem 400 may be partitioned as a boost mode converter, synchronousbuck converter, and a parallel resonant amplifier. According to oneembodiment, a resonant mode boost converter section of the medicalinstrument 100 may be employed to convert the DC battery 300 voltage toa higher DC voltage for use by the synchronous mode buck converter. Oneaspect to consider for achieving a predetermined efficiency of theresonant mode boost converter section is ratio between input and outputvoltages of the boost converter. In one embodiment, although a 10:1ratio is achievable, the cost is that for any appreciable power on thesecondary the input currents to the boost mode transformer become quiteheavy, in the range of about 15-25 A, depending on the load.

In another embodiment a transformer turns ratio of about 5:1 isprovided. It will be appreciated that transformer ratios in the range ofabout 5:1 to about 10:1 also may be implemented, without limitation. Ina 5:1 transformer turns ratio, the design tradeoff is managing the Q ofthe parallel resonant output against the boost ratio. The resonantoutput network performs two functions. First, it filters the square,digital pulses from the Class D output amplifier and removes all but thefundamental frequency sine wave from the output. Second, it provides apassive voltage gain due to the Q of the filter network. In other words,current from the amplifier is turned into output voltage, at a gaindetermined by the circuit's unloaded Q and the load resistance, whichaffects the Q of the circuit.

Another aspect to consider for achieving a predetermined efficiency inthe resonant mode boost converter section is to utilize a full bridgeswitcher topology, which allows half the turns ratio for the boosttransformer for the same input voltage. The tradeoff is that thisapproach may require additional FET transistors, e.g., an additional twoFETs are required over a half bridge approach, for example. Presentlyavailable switchmode FETs, however, are relatively small, and while thegate drive power is not negligible, it provides a reasonable designtradeoff.

Yet another aspect to consider for achieving a predetermined efficiencyin the resonant mode boost converter section and operating the boostconverter at maximum efficiency, is to always run the circuit at theresonant frequency so that the FETs are always switching at either avoltage or current minima, whichever is selected by the designer (ZCSvs. ZVS switching), for example. This can include monitoring theresonant frequency of the converter as the load changes, and makingadjustments to the switching frequency of the boost converter to allowZVS or ZCS (Zero Voltage Switching/Zero Current Switching) to occur forminimum power dissipation.

Yet another aspect to consider for achieving a predetermined efficiencyin the resonant mode boost converter section is to utilize a synchronousrectifier circuit instead of a conventional full-wave diode rectifierblock. Synchronous rectification employs FETs as diodes because theon-resistance of the FET is so much lower than that of even a Schottkypower diode optimized for low forward voltage drop under high currentconditions. A synchronous rectifier requires gate drive for the FETs andthe logic to control them, but offers significant power savings over atraditional full bridge rectifier.

In accordance with various embodiments, the predetermined efficiency ofa resonant mode boost converter is approximately 98-99% input to output,for example. Any suitable predetermined efficiency may be selected basedon the particular implementation. Accordingly, the embodiments describedherein are limited in this context.

According to one embodiment, a synchronous buck converter section of themedical instrument 100 may be employed to reduce the DC voltage fed tothe RF amplifier section to the predetermined level to maintain thecommanded output power, voltage or current as dictated by the loadcurve, with as little loss as is possible. The buck converter isessentially an LC lowpass filter fed by a low impedance switch, alongwith a regulation circuit to control the switch to maintain thecommanded output voltage. The operating voltage is dropped to thepredetermined level commanded by the main controller, which is runningthe control system code to force the system to follow the assigned loadcurve as a function of sensed tissue resistance. In accordance withvarious embodiments, the predetermined efficiency of a synchronous buckregulator is approximately 99%, for example. Any suitable predeterminedefficiency may be selected based on the particular implementation.Accordingly, the embodiments described herein are limited in thiscontext.

According to one embodiment, a resonant mode RF amplifier sectioncomprising a parallel resonant network on the RF amplifier sectionoutput is provided. In one embodiment, a predetermined efficiency may beachieved by a providing a parallel resonant network on the RF amplifiersection output. The RF amplifier section may be driven at the resonantfrequency of the output network which accomplished three things. First,the high Q network allows some passive voltage gain on the output,reducing the boost required from the boost regulator in order to producehigh voltage output levels. Second, the square pulses produced by the RFamplifier section are filtered and only the fundamental frequency isallowed to pass to the output. Third, a full-bridge amplifier isswitched at the resonant frequency of the output filter, which is to sayat either the voltage zero crossings or the current zero crossings inorder to dissipate minimum power. Accordingly, a predeterminedefficiency of the RF amplifier section is approximately 98%. Gate drivelosses may limit the efficiency to this figure or slightly lower. Anysuitable predetermined efficiency may be selected based on theparticular implementation. Accordingly, the embodiments described hereinare limited in this context.

In view of the RF instrument topology and architecture described above,an overall system efficiency of approximately 0.99*0.99*0.98, which isapproximately 96%, may be achieved. Accordingly, to deliverapproximately 45 W, approximately 1.8 W would be dissipated by theelectronics exclusive of the power required to run the main andhousekeeping microprocessors, and the support circuits such as the ADCand analog amplifiers and filters. To deliver approximately 135 W,approximately 5.4 W would be dissipated. This is the amount of powerthat would be required to implement a large jaw class generator in ahand held electrosurgical medical instrument. Overall system efficiencywould likely only be a weak function of load resistance, instead of arelatively strong one as it may be the case in some conventionalinstruments.

In various other embodiments of the electrosurgical medical instrument100, a series resonant topology may be employed to achieve certainpredetermined efficiency increase by employing a full bridge amplifierfor the primary circuit and isolate the full bridge amplifier fromground to get more voltage on the primary. This provides a largerprimary inductance and lower flux density due to the larger number ofturns on the primary.

FIG. 22 illustrates an RF drive and control circuit 800, according toone embodiment. FIG. 22 is a part schematic part block diagramillustrating the RF drive and control circuitry 800 used in thisembodiment to generate and control the RF electrical energy supplied tothe forceps 108. As will be explained in more detail below, in thisembodiment, the drive circuitry 800 is a resonant mode RF amplifiercomprising a parallel resonant network on the RF amplifier output andthe control circuitry operates to control the operating frequency of thedrive signal so that it is maintained at the resonant frequency of thedrive circuit, which in turn controls the amount of power supplied tothe forceps 108. The way that this is achieved will become apparent fromthe following description.

As shown in FIG. 22, the RF drive and control circuit 800 comprises theabove described battery 300 are arranged to supply, in this example,about 0V and about 12V rails. An input capacitor (C_(in)) 802 isconnected between the 0V and the 12V for providing a low sourceimpedance. A pair of FET switches 803-1 and 803-2 (both of which areN-channel in this embodiment to reduce power losses) is connected inseries between the 0V rail and the 12V rail. FET gate drive circuitry805 is provided that generates two drive signals—one for driving each ofthe two FETs 803. The FET gate drive circuitry 805 generates drivesignals that causes the upper FET (803-1) to be on when the lower FET(803-2) is off and vice versa. This causes the node 807 to bealternately connected to the 12V rail (when the FET 803-1 is switchedon) and the 0V rail (when the FET 803-2 is switched on). FIG. 22 alsoshows the internal parasitic diodes 808-1 and 808-2 of the correspondingFETs 803, which conduct during any periods that the FETs 803 are open.

As shown in FIG. 22, the node 807 is connected to an inductor-inductorresonant circuit 810 formed by an inductor L_(s) 812 and an inductorL_(m) 814, which is the primary coil of a transformer 815. Thetransformer 815 is the schematic symbol for the transformer 404 shown inFIGS. 8 and 10 and described in more detail below in connection withFIGS. 23-35. Turning back to FIG. 22, the FET gate driving circuitry 805is arranged to generate drive signals at a drive frequency (f_(d)) thatopens and crosses the FET switches 803 at the resonant frequency of theparallel resonant circuit 810. As a result of the resonantcharacteristic of the resonant circuit 810, the square wave voltage atnode 807 will cause a substantially sinusoidal current at the drivefrequency (f_(d)) to flow within the resonant circuit 810. Asillustrated in FIG. 22, the inductor L_(m) 814 is the primary coil of atransformer 815, the secondary coil of which is formed by inductorL_(sec) 816. The inductor L_(sec) 816 of the transformer 815 secondaryis connected to a resonant circuit 817 formed by inductor L₂, capacitorC₄ 820, capacitor C₂ 822, and capacitor C₃ 825. The transformer 815up-converts the drive voltage (V_(d)) across the inductor L_(m) 814 tothe voltage that is applied to the output parallel resonant circuit 817.The load voltage (V_(L)) is output by the parallel resonant circuit 817and is applied to the load (represented by the load resistance R_(load)819 in FIG. 22) corresponding to the impedance of the forceps' jaws andany tissue or vessel gripped by the forceps 108. As shown in FIG. 15, apair of DC blocking capacitors C_(bl) 840-1 and 840-2 is provided toprevent any DC signal being applied to the load 819.

In one embodiment, the transformer 815 may be implemented with a CoreDiameter (mm), Wire Diameter (mm), and Gap between secondary windings inaccordance with the following specifications:

Core Diameter, D (mm)

D=19.9×10-3

Wire diameter, W (mm) for 22 AWG wire

W=7.366×10-4

Gap between secondary windings, in gap=0.125

G=gap/25.4

In this embodiment, the amount of electrical power supplied to theforceps 108 is controlled by varying the frequency of the switchingsignals used to switch the FETs 803. This works because the resonantcircuit 810 acts as a frequency dependent (loss less) attenuator. Thecloser the drive signal is to the resonant frequency of the resonantcircuit 810, the less the drive signal is attenuated. Similarly, as thefrequency of the drive signal is moved away from the resonant frequencyof the circuit 810, the more the drive signal is attenuated and so thepower supplied to the load reduces. In this embodiment, the frequency ofthe switching signals generated by the FET gate drive circuitry 805 iscontrolled by a controller 841 based on a desired power to be deliveredto the load 819 and measurements of the load voltage (V_(L)) and of theload current (I_(L)) obtained by conventional voltage sensing circuitry843 and current sensing circuitry 845. The way that the controller 841operates will be described in more detail below.

In one embodiment, the voltage sensing circuitry 843 and the currentsensing circuitry 845 may be implemented with high bandwidth, high speedrail-to-rail amplifiers (e.g., LMH6643 by National Semiconductor). Suchamplifiers, however, consume a relatively high current when they areoperational. Accordingly, a power save circuit may be provided to reducethe supply voltage of the amplifiers when they are not being used in thevoltage sensing circuitry 843 and the current sensing circuitry 845. Inone-embodiment, a step-down regulator (e.g., LT3502 by LinearTechnologies) may be employed by the power save circuit to reduce thesupply voltage of the rail-to-rail amplifiers and thus extend the lifeof the battery 300.

In one embodiment, the transformer 815 and/or the inductor L_(s) 812 maybe implemented with a configuration of litz wire conductors to minimizethe eddy-current effects in the windings of high-frequency inductivecomponents. These effects include skin-effect losses and proximityeffect losses. Both effects can be controlled by the use of litz wire,which are conductors made up of multiple individually insulated strandsof wire twisted or woven together. Although the term litz wire isfrequently reserved for conductors constructed according to a carefullyprescribed pattern, in accordance with the present disclosure, any wirestrands that are simply twisted or grouped together may be referred toas litz wire. Accordingly, as used herein, the term litz wire refers toany insulated twisted or grouped strands of wires.

By way of background, litz wire can reduce the severe eddy-currentlosses that otherwise limit the performance of high-frequency magneticcomponents, such as the transformer 815 and/or the inductor L_(s) 812used in the RF drive and control circuit 800 of FIG. 22. Although litzwire can be very expensive, certain design methodologies providesignificant cost reduction without significant increases in loss, ormore generally, enable the selection of a minimum loss design at anygiven cost. Losses in litz-wire transformer windings have beencalculated by many authors, but relatively little work addresses thedesign problem of how to choose the number and diameter of strands for aparticular application. Cost-constrained litz wire configurations aredescribed in C. R. Sullivan, “Cost-Constrained Selection of Strand Wireand Number in a Litz-Wire Transformer Winding,” IEEE Transactions onPower Electronics, vol. 16, no. 2, pp. 281-288, which is incorporatedherein by reference. The choice of the degree of stranding in litz wirefor a transformer winding is described in C. R. Sullivan, “OptimalChoice for Number of Strands in a Litz-Wire Transformer Winding,” IEEETransactions on Power Electronics, vol. 14, no. 2, pp. 283-291, which isincorporated herein by reference.

In one embodiment, the transformer 815 and/or the inductor L_(s) 812 maybe implemented with litz wire by HM Wire International, Inc., of Canton,Ohio or New England Wire Technologies of Lisbon, N.H., which has aslightly different construction in terms of the number of strands in theintermediate windings, but has the same total number of strands ofeither 44 gauge or 46 gauge wire by HM Wire International, Inc.Accordingly, the disclosure now turns to FIGS. 23-35, which illustrateone embodiment of the transformer 815 and the inductor L_(s) 812implemented with litz wire.

FIG. 23 illustrates a perspective view of one embodiment of thetransformer 404 shown in FIGS. 8 and 10 and shown as transformer 815 inconnection with the RF drive circuit 800 illustrated in FIG. 22. Asshown in FIG. 23, in one embodiment, the transformer 404 comprises abobbin 804, a ferrite core 806, a primary coil 821 (e.g., inductor L_(m)814 in FIG. 22), and a secondary coil 823 (e.g., inductor L_(sec) 816 inFIG. 22). In one embodiment, the bobbin 804 may be a 10-pin surfacemounted device (SMD) provided by Ferroxcube International Holding B.V.In one embodiment, the ferrite core 806 may be an EFD 20/107 N49. In oneembodiment, the transformer 815 has a power transfer of ˜45 W, a maximumsecondary current of ˜1.5 A RMS, maximum secondary voltage of ˜90V RMS,maximum primary current of ˜15.5 A RMS, and a turns ratio of 20:2(secondary turns:primary turns), for example. The operating frequencyrange of the transformer 404 is from ˜370 kHz to ˜550 kHz, and apreferred frequency of ˜430 kHz. It will be appreciated that thesespecification are provided as examples and should not be construed to belimiting of the scope of the appended claims.

In one embodiment, the transformer 404 comprises a ferrite core materialhaving particular characteristics. The core used for both the inductor406 and the transformer 404, albeit with a different gap to yield therequired A_(L) for each component. A_(L) has units of Henrys/turns², sothe inductance of a winding may be found by using NTURNS²*A_(L). In oneembodiment, an A_(L) of 37 is used for the inductor 406, and an A_(L) of55 is used for the transformer 406. This corresponds to a gap ofapproximately 0.8 mm and 2.0 mm respectively, although the A_(L) or theinductance is the parameter to which the manufacturing process controls,with the A_(L) being an intermediate quantity that we are not measuringdirectly.

In one embodiment, the inductance of the inductor 406 and transformer404 winding may be measured directly with “golden bobbins,” which aresquarely in the middle of the tolerance bands for the windingstatistical distributions. Cores that are ground are then tested usingthe “golden bobbin” to assess whether the grind is good on the cores.Better results were yielded than the industry standard method, which isto fill a bobbin with as many windings as they can fit on the bobbin,and then back calculating the A_(L) of the core, and controlling A_(L)instead of the inductance. It was found that using a “golden bobbin” inthe manufacturing process yielded better results. The bobbin is what thecopper windings are secured to, and the ferrite E cores slip through ahole in the bobbin, and are secured with clips.

FIG. 24 illustrates a perspective view of one embodiment of the primarycoil 821 (e.g., inductor L_(m) 814 in FIG. 22) of the transformer 404illustrated in FIG. 23. In one embodiment, the primary coil 821 windingsmay be constructed using 300 strand/46 gauge litz wire as indicated inTABLE 1 below, among other suitable configurations. In one embodiment,primary coil 821 has an inductance of ˜270 nH, an AC resistance<46 mΩ,and a DC resistance of ≦5 mΩ, for example.

TABLE 1 Primary Coil 821 (L_(m)814) 46 Gauge Litz Wire 300 Strands 46AWG - 24 turns per foot (TPF) Single Build MW80 155*C Single NylonServed Construction: 5 × 3 × 20/46 AWG Ft per lb: 412 Nominal OD: 0.039″Nominal

FIG. 26 illustrates a bottom view of the primary coil 821 (e.g.,inductor L_(m) 814 in FIG. 22) illustrated in FIG. 24. FIG. 27illustrates a side view of the primary coil 821 illustrated in FIG. 24.FIG. 28 illustrates a sectional view of the primary coil 821 illustratedin FIG. 24 taken along section 28-28.

FIG. 25 illustrates a perspective view of one embodiment of a secondarycoil 823 (e.g., inductor L_(sec) 816 in FIG. 22) of the transformer 404illustrated in FIG. 23. In one embodiment, the secondary coil 823windings may be constructed using 105 strand/44 gauge litz wire asindicated in TABLE 2 below, among other suitable configurations. In oneembodiment, the secondary coil 823 has an inductance of 22 μH±5% @430kHz, an AC resistance<2.5Ω, and a DC resistance ≦80 mΩ, for example.

TABLE 2 Secondary Coil 823 (L_(sec) 816) 44 Gauge Litz Wire 105 Strands44 AWG 24 TPF Single Build MW80 155*C Single Nylon Served Construction:5 × 21/44 AWG Ft per lb: 1214 Nominal OD: 0.023″ Nominal

FIG. 29 illustrates a bottom view of the secondary coil 823 (e.g.,inductor L_(sec) 816 in FIG. 22) illustrated in FIG. 25. FIG. 30illustrates a side view of the secondary coil 823 illustrated in FIG.25. FIG. 31 illustrates a sectional view of the secondary coil 823illustrated in FIG. 30 taken along section 31-31.

FIG. 32 is a perspective view of one embodiment of the inductor 406shown in FIGS. 8 and 10 and shown as inductor L_(s) 812 in connectionwith the RF drive circuit 800 illustrated in FIG. 22. As shown in FIG.32, in one embodiment, the inductor 406 comprises a bobbin 809, aferrite core 811, and a coil 813. In one embodiment, the bobbin 809 maybe a 10-pin surface mounted device (SMD) provided by FerroxcubeInternational Holding B.V. In one embodiment, the ferrite core 811 maybe an EFD 20/107 N49. In one embodiment, the coil 813 windings may beconstructed using 300 strand/46 gauge litz wire wound at 24 TPF. In oneembodiment, the inductor L_(s) 812 may have an inductance of ˜345 nH±6%@430 kHz, an AC resistance<50 mΩ, and a DC resistance ≦7 mΩ, forexample. The operating frequency range of the inductor L_(s) 812 is from˜370 kHz to ˜550 kHz, and a preferred frequency of ˜430 kHz, and anoperating current of ˜15.5 A rms. It will be appreciated that thesespecification are provided as examples and should not be construed to belimiting of the scope of the appended claims.

FIG. 33 illustrates a bottom view of the inductor 406 (e.g., inductorL_(s) 812 in FIG. 22) illustrated in FIG. 32. FIG. 34 illustrates a sideview of the inductor 406 illustrated in FIG. 32. FIG. 35 illustrates asectional view of the inductor 406 illustrated in FIG. 34 taken alongsection 35-35.

Accordingly, as described above in connection with FIGS. 23-35, in oneembodiment, the transformer 404 (e.g., transformer 815) and/or theinductor 406 (e.g., inductor 812) used in the RF drive and controlcircuit 800 of FIG. 22 may be implemented with litz wire. One litz wireconfiguration may be produced by twisting 21 strands of 44 AWG SPN wireat 18 twists per foot (left direction twisting). Another litz wireconfiguration may be produced by twisting 5×21/44 AWG (105/44 AWG SPN),also at 18 twists per foot (left direction twisting). Other litz wireconfigurations include 300/46 AWG litz wire as well as 46 AWG or finergauge size wire.

FIG. 36 illustrates the main components of the controller 841, accordingto one embodiment. In the embodiment illustrated in FIG. 36, thecontroller 841 is a microprocessor based controller and so most of thecomponents illustrated in FIG. 22 are software based components.Nevertheless, a hardware based controller 841 may be used instead. Asshown, the controller 841 includes synchronous I, Q sampling circuitry851 that receives the sensed voltage and current signals from thesensing circuitry 843 and 845 and obtains corresponding samples whichare passed to a power, V_(rms) and I_(rms) calculation module 853. Thecalculation module 853 uses the received samples to calculate the RMSvoltage and RMS current applied to the load 819 (FIG. 22; forceps 108and tissue/vessel gripped thereby) and from them the power that ispresently being supplied to the load 839. The determined values are thenpassed to a frequency control module 855 and a medical device controlmodule 857. The medical device control module 857 uses the values todetermine the present impedance of the load 819 and based on thisdetermined impedance and a pre-defined algorithm, determines what setpoint power (P_(set)) should be applied to the frequency control module855. The medical device control module 857 is in turn controlled bysignals received from a user input module 859 that receives inputs fromthe user (for example pressing buttons or activating the control levers114, 110 on the handle 104) and also controls output devices (lights, adisplay, speaker or the like) on the handle 104 via a user output module861.

The frequency control module 855 uses the values obtained from thecalculation module 853 and the power set point (P_(set)) obtained fromthe medical device control module 857 and predefined system limits (tobe explained below), to determine whether or not to increase or decreasethe applied frequency. The result of this decision is then passed to asquare wave generation module 863 which, in this embodiment, incrementsor decrements the frequency of a square wave signal that it generates by1 kHz, depending on the received decision. As those skilled in the artwill appreciate, in an alternative embodiment, the frequency controlmodule 855 may determine not only whether to increase or decrease thefrequency, but also the amount of frequency change required. In thiscase, the square wave generation module 863 would generate thecorresponding square wave signal with the desired frequency shift. Inthis embodiment, the square wave signal generated by the square wavegeneration module 863 is output to the FET gate drive circuitry 805,which amplifies the signal and then applies it to the FET 803-1. The FETgate drive circuitry 805 also inverts the signal applied to the FET803-1 and applies the inverted signal to the FET 803-2.

FIG. 37 is a signal plot illustrating the switching signals applied tothe FETs 803, a sinusoidal signal representing the measured current orvoltage applied to the load 819, and the timings when the synchronoussampling circuitry 851 samples the sensed load voltage and load current,according to one embodiment. In particular, FIG. 37 shows the switchingsignal (labeled PWM1 H) applied to upper FET 803-1 and the switchingsignal (labeled PWM1 L) applied to lower FET 803-2. Although notillustrated for simplicity, there is a dead time between PWM1 H and PWM1L to ensure that that both FETs 803 are not on at the same time. FIG. 17also shows the measured load voltage/current (labeled OUTPUT). Both theload voltage and the load current will be a sinusoidal waveform,although they may be out of phase, depending on the impedance of theload 819. As shown, the load current and load voltage are at the samedrive frequency (f) as the switching Signals (PWM1 H and PWM1 L) used toswitch the FETs 803. Normally, when sampling a sinusoidal signal, it isnecessary to sample the signal at a rate corresponding to at least twicethe frequency of the signal being sampled—i.e. two samples per period.However, as the controller 841 knows the frequency of the switchingsignals, the synchronous sampling circuit 851 can sample the measuredvoltage/current signal at a lower rate. In this embodiment, thesynchronous sampling circuit 851 samples the measured signal once perperiod, but at different phases in adjacent periods. In FIG. 37, this isillustrated by the “I” sample and the “Q” sample. The timing that thesynchronous sampling circuit 51 makes these samples is controlled, inthis embodiment, by the two control signals PWM2 and PWM3, which have afixed phase relative to the switching signals (PWM1 H and PWM1 L) andare out of phase with each other (preferably by quarter of the period asthis makes the subsequent calculations easier). As shown, thesynchronous sampling circuit 851 obtains an “I” sample on every otherrising edge of the PWM2 signal and the synchronous sampling circuit 851obtains a “0” sample on every other rising edge of the PWM3 signal. Thesynchronous sampling circuit 851 generates the PWM2 and PWM3 controlsignals from the square wave signal output by the square wave generator863 (which is at the same frequency as the switching signals PWM1 HandPWM1 L). Thus control signals PWM2 and PWM3 also changes (whilst theirrelative phases stay the same). In this way, the sampling circuitry 851continuously changes the timing at which it samples the sensed voltageand current signals as the frequency of the drive signal is changed sothat the samples are always taken at the same time points within theperiod of the drive signal. Therefore, the sampling circuit 851 isperforming a “synchronous” sampling operation instead of a moreconventional sampling operation that just samples the input signal at afixed sampling rate defined by a fixed sampling clock.

The samples obtained by the synchronous sampling circuitry 851 are thenpassed to the power, V_(rms) and I_(rms) calculation module 853 whichcan determine the magnitude and phase of the measured signal from justone “I” sample and one “Q” sample of the load current and load voltage.However, in this embodiment, to achieve some averaging, the calculationmodule 853 averages consecutive “I” samples to provide an average “I”value and consecutive “Q” samples to provide an average “0” value; andthen uses the average I and Q values to determine the magnitude andphase of the measured signal (in a conventional manner). As thoseskilled in the art will appreciate, with a drive frequency of about 400kHz and sampling once per period means that the synchronous samplingcircuit 851 will have a sampling rate of 400 kHz and the calculationmodule 853 will produce a voltage measure and a current measure every0.01 ms. The operation of the synchronous sampling circuit 851 offers animprovement over existing products, where measurements can not be madeat the same rate and where only magnitude information is available (thephase information being lost).

In one embodiment, the RF amplifier and drive circuitry for theelectrosurgical medical instrument 100 employs a resonant mode step-upswitching regulator, running at the desired RF electrosurgical frequencyto produce the required tissue effect. The waveform illustrated in FIG.18 can be employed to boost system efficiency and to relax thetolerances required on several custom components in the electronicssystem 400. In one embodiment, a first generator control algorithm maybe employed by a resonant mode switching topology to produce the highfrequency, high voltage output signal necessary for the medicalinstrument 100. The first generator control algorithm shifts theoperating frequency of the resonant mode converter to be nearer orfarther from the resonance point in order to control the voltage on theoutput of the device, which in turn controls the current and power onthe output of the device. The drive waveform to the resonant modeconverter has heretofore been a constant, fixed duty cycle, withfrequency (and not amplitude) of the drive waveform being the only meansof control.

FIG. 38 illustrates a drive waveform for driving the FET gate drivecircuitry 805, according to one embodiment. Accordingly, in anotherembodiment, a second generator control algorithm may be employed by aresonant mode switching topology to produce the high frequency, highvoltage output signal necessary for the medical instrument 100. Thesecond generator control algorithm provides an additional means ofcontrol over the amplifier in order to reduce power output in order forthe control system to track the power curve while maintaining theoperational efficiency of the converter. As shown in FIG. 38, accordingto one embodiment, the second generator control algorithm is configuredto not only modulate the drive frequency that the converter is operatingat, but to also control the duty cycle of the drive waveform by dutycycle modulation. Accordingly, the drive waveform 890 illustrated inFIG. 38 exhibits two degrees of freedom. Advantages of utilizing thedrive waveform 890 modulation include flexibility, improved overallsystem efficiency, and reduced power dissipation and temperature rise inthe amplifier's electronics and passive inductive components, as well asincreased battery life due to increased system efficiency.

FIG. 39 illustrates a diagram of the digital processing system 900located on the first substrate 408 a, according to one embodiment. Thedigital processing system 900 comprises a main processor 902, a safetyprocessor 904, a controller 906, a memory 908, and a non-volatile memory402, among other components that are not shown for clarity ofdisclosure. The dual processor architecture comprises a first operationprocessor referred to as the main processor 902, which is the primaryprocessor for controlling the operation of the medical instrument 100.In one aspect, the main processor 902 executes the software instructionsto implement the controller 841 shown in FIG. 16. In one embodiment, themain processor 902 also may comprise an analog-to-digital (A/D)converter and pulse width modulators (PWM) for timing control.

The main processor 902 controls various functions of the overall medicalinstrument 100. In one embodiment, the main processor receives voltagesense (V Sense) and current sense (I Sense) signals measured at the load(represented by the load resistance R_(load) 819 in FIG. 22)corresponding to the impedance of the forceps' jaws and any tissue orvessel gripped by the forceps 108. For example, the main processor 902receives the V Sense and I Sense signals for the voltage sensingcircuitry 843 and current sensing circuitry 845, as shown in FIG. 15.The main processor 902 also receives tissue temperature (T sense)measurement at the load. Using the V Sense, I Sense, and T Sense, theprocessor 902 can execute a variety of algorithms to detect the state ofthe tissue based on impedance Z, where Z=V Sense/I Sense. In oneembodiment, the medical instrument 100 is frequency agile from about 350kHz to about 650 kHz. As previously discussed, the controller 841changes the resonant operating frequency of the RF amplifier sections,controlling the pulse width modulation (PWM), reducing the outputvoltage (V) to the load, and enhancing the output current (I) to theload as described in connection with FIGS. 22 and 36-38, for example.

Examples of frequency agile algorithms that may be employed to operatethe present surgical instrument 100 are described in the followingcommonly owned U.S. patent applications, each of which is incorporatedherein by reference in its entirety: (1) U.S. patent application Ser.No. 12/896,351, entitled DEVICES AND TECHNIQUES FOR CUTTING ANDCOAGULATING TISSUE, Attorney Docket No. END6427USCIP1/080591CIP; (2)U.S. patent application Ser. No. 12/896,479, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP1/100557; (3) U.S. patent application Ser. No. 12/896,345,entitled SURGICAL GENERATOR FOR ULTRASONIC AND ELECTROSURGICAL DEVICES,Attorney Docket No. END6673USNP2/100559; (4) U.S. patent applicationSer. No. 12/896,384, entitled SURGICAL GENERATOR FOR ULTRASONIC ANDELECTROSURGICAL DEVICES, Attorney Docket No. END6673USNP3/100560; (5)U.S. patent application Ser. No. 12/896,467, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP4/100562; (6) U.S. patent application Ser. No. 12/896,451,entitled SURGICAL GENERATOR FOR ULTRASONIC AND ELECTROSURGICAL DEVICES,Attorney Docket No. END6673USNP5/100563; (7) U.S. patent applicationSer. No. 12/896,470, entitled SURGICAL GENERATOR FOR ULTRASONIC ANDELECTROSURGICAL DEVICES, Attorney Docket No. END6673USNP6/100564; andU.S. patent application Ser. No. 12/503,775, entitled ULTRASONIC DEVICEFOR CUTTING AND COAGULATING WITH STEPPED OUTPUT, Attorney Docket No.END6427USNP/08059.

In one embodiment, the main processor 902 also detects the limit switchend of stroke position (Lmt Sw Sense). The limit switch is activatedwhen the knife reaches the end of stroke limit. The signal generated bythe limit switch Lmt Sw Sense is provided to the main processor 902 toindicate the end-of-stroke condition of the knife.

In one embodiment, the main processor 902 also senses an actuationsignal (Reed Sw Sense) associated with the magnetically operated element606 located on the electronics system 400. As previously described themagnetically operated element 606 is initially actuated when theinitialization clip 600, 650 is removed. When the Reed Sw Sense isdetected by the main processor 902, an algorithm is executed to controlthe operation of the medical instrument 100. One embodiment of such analgorithm is described in more detail hereinbelow. Further, on initialpower up, when the magnetically operated element 606 connects thebattery 300 supply to the electronics system 400, a low resistance loadis applied to the terminals of the battery 300 to check the internalresistance of the battery 300. This enables the main processor 902 todetermine the charge state of the battery 300 or in other words,determines the ability of the battery 300 to deliver power to theelectronics system 400. In one embodiment, the main processor 902 maysimply determine the absolute value of the difference between theunloaded and loaded battery 300. If the main processor 902 determinesthat the battery 300 does not have enough capacity to deliver a suitableamount of power, the main processor 902 disables the medical instrument100 and outputs a Discharge Battery signal, as discussed in more detailhereinbelow, to controllably discharge the battery 300 such that itcannot be reused and is classified as an out-of-the box failure.

In one embodiment, as part of the algorithm, the main processor 902enables one or more visual feedback elements 118. As shown in FIG. 39,the visual feedback elements 118 comprise at least one red LED, at leastone green LED, and at least one blue LED. Each of the LEDs are energizedbased on algorithms associated with the medical instrument 100. The mainprocessor 902 also actuates an audio feedback element 410 based onalgorithm associated with the medical instrument 100. In one embodiment,the audio feedback element 410 includes a piezoelectric buzzer operatingat 65 dBa at 1 meter at a frequency between about 2.605 kHz to 2.800kHz, for example. As previously discussed, the visual and audio feedbackelements 118, 410 are not limited to the devices disclosed herein andare intended to encompass other visual and audio feedback elements.

In one embodiment, the main processor 902 executes battery shut-off andbattery-drain/kill algorithms to shut-off the instrument 100 and/ordrain the battery 300 under certain conditions described below. Thealgorithms monitor instrument usage and battery voltage and triggershutdown of the instrument 100 and the drain the battery 300 in theevent of unrecoverable faults or as a natural way to shutdown theinstrument 100 and drain the battery 300.

In one embodiment, an unrecoverable event triggers the medicalinstrument 100 to shutdown and drain the battery 330. Events that cantrigger the medical instrument 100 to shutdown and drain the battery 300include, without limitation, (1) the detection of five consecutivefiring short circuits; (2) activation of RF power when the activationbutton 114 is not pressed; (3) activation of RF power without activationof the audible feedback; (4) activation of the audible feedback withoutRF power; (5) the switch is stuck at power up for >30 seconds; (6) theresting voltage of the battery 300 is less than 10.848V after anyfiring; and (7) three consecutive firings that are over or under theestablished load curve extremes of +/−20%.

In one embodiment, the medical instrument 100 may be shutdown and thebattery 300 drained as a result natural usage of the instrument 100,which includes, without limitation: (1) when the medical instrument 100completes five firings after detecting a resting voltage of the battery300 of 11.02V; (2) after the clip 600, 650 has been removed from themedical instrument 100, if the instrument 100 has completed a realfiring (more than three joules and the user gets the cycle completetone3) and if the user replaces the initialization clip 600, 650 on theinstrument 100, the instrument 100 will no longer be useable when theyclip 600, 650 is once again removed from the instrument 100; (3) whenthe user depresses the disposal button 120 located on the bottom of thehandle 104 of the instrument 100 for four seconds; (4) upon reaching atime limit: (a) after at least eight hours of use and if not usedbetween hours six through eight, the instrument 100 it will shutdown;and (b) if used at least once between hours six and eight, theinstrument 100 will extend the time limit to ten hours and thenshutdown.

In one embodiment, the main processor 902 provides certain outputsignals. For example, one output signal is provided to the circuitry todischarge the battery 300 (Discharge Battery) signal. This is explainedin more detail with reference to FIG. 40. There may be a need todischarge the battery 300 under several conditions according toalgorithms associated with the medical instrument 100. Such conditionsand algorithm are discussed in more detail hereinbelow. In oneembodiment, the battery 300 used to power the medical instrument 100 hasan initial out of the box capacity ranging from about 6 to about 8 hoursup to about 10 hours under certain circumstances. After a medicalprocedure, some capacity will remain in the battery 300. Since thebattery 300 is designed as a single use battery and is not rechargeable,the battery 300 is controllably discharged after use to prevent reuse ofthe medical instrument 100 when the battery 300 has a partial capacity.

In one embodiment, the main processor 902 can verify the output voltage(V) and current (I) sensing function by an artificial injection ofvoltage and current into the load. The main processor 902 then readsback the voltage and current from the load and determines whether themedical instrument 100 can operate or fail in safe mode. In oneembodiment, the test voltage and current are applied to the dummy loadvia an electronically controlled switch. For example, the electronicswitch may comprise a two-pole relay. The main processor 902 verifiesthe output sensing function once per hour when it is inactive and onceprior to every firing. It will be appreciated that these periods mayvary based on the particular implementation. To verify the outputsensing function, the main processor 902 outputs inject test voltage(Inject Test V) and inject test current (Inject test I) signals to theoutput sensing test circuit described in connection with FIG. 41hereinbelow. As previously described, the main processor 902 reads thesensed voltage and current signals V Sense and I Sense to determine theoperation of the voltage (V) and current (I) sensing function of themedical instrument 100.

The main processor 902 is also coupled to a memory 908 and thenonvolatile memory 402. The computer program instructions executed bythe main processor 902 are stored in the nonvolatile memory 902 (e.g.,EEPROM, FLASH memory, and the like). The memory 908, which may be randomaccess memory (RAM) may be used for storing instructions duringexecution, measured data, variables, among others. The memory 908 isvolatile and its contents are erased when the battery 300 is dischargedbelow a predetermine voltage level. The nonvolatile memory 402 isnonvolatile and its contents are not erased when the battery 300 isdischarged below a predetermined level. In one embodiment, it may bedesirable to erase the contents of the nonvolatile memory 402 to preventits reuse, for example, when the medical instrument 100 has already beenutilized in a procedure, the instrument 100 is determined to be anout-of-the box failure, or when the instrument 100 otherwise fails. Ineach of these circumstances, the main processor 902 initiates a battery300 discharge operation. In such circumstances, program instructions inthe nonvolatile memory 402 for erasing nonvolatile memory aretransferred to the memory 908 where program execution resumes. Theinstructions executed from the memory 908 then erase the contents of thenonvolatile memory 402.

The safety processor 904 is coupled to the main processor 902 andmonitors the operation of the main processor 902. If the safetyprocessor 904 determines a malfunction of the main processor 902, thesafety processor 904 can disable the operation of the main processor 902and shuts down the medical instrument 100 in a safe mode.

The controller 906 is coupled to both the main processor 902 and thesafety processor 904. In one embodiment, the controller 906 alsomonitors the operation of the main processor 902 and if the mainprocessor 902 loses control, the controller 906 enables the safetyprocessor to shut down the RF amplifier section in a safe manner. In oneembodiment the controller 906 may be implemented as complex programmablelogic device (CPLD), without limitation.

To preserve or extend the life of the battery 300, the main processor902, the safety processor 904, and/or the controller 906 may be powereddown (e.g., placed in sleep mode) when they are not in use. This enablesthe digital processing system 900 to conserve energy to preserve orextend the life of the battery 300.

In various embodiments, the main processor 902, the safety processor904, or the controller 906 may comprise several separate functionalelements, such as modules and/or blocks. Although certain modules and/orblocks may be described by way of example, it can be appreciated that agreater or lesser number of modules and/or blocks may be used and stillfall within the scope of the embodiments. Further, although variousembodiments may be described in terms of modules and/or blocks tofacilitate description, such modules and/or blocks may be implemented byone or more than one hardware component, e.g., processor, ComplexProgrammable Logic Device (CPLD), Digital Signal Processor (DSP),Programmable Logic Devices (PLD), Application Specific IntegratedCircuit (ASIC), circuits, registers and/or software components, e.g.,programs, subroutines, logic and/or combinations of hardware andsoftware components.

In one embodiment, the digital processing system 900 may comprise one ormore embedded applications implemented as firmware, software, hardware,or any combination thereof. The digital processing system 900 maycomprise various executable modules such as software, programs, data,drivers, application program interfaces (APIs), and so forth. Thefirmware may be stored in the nonvolatile memory 402 (NVM), such as inbit-masked read-only memory (ROM) or flash memory. In variousimplementations, storing the firmware in ROM may preserve flash memory.The NVM may comprise other types of memory including, for example,programmable ROM (PROM), erasable programmable ROM (EPROM), electricallyerasable programmable ROM (EEPROM), or battery backed random-accessmemory 908 (RAM) such as dynamic RAM (DRAM), Double-Data-Rate DRAM(DDRAM), and/or synchronous DRAM (SDRAM).

FIG. 40 illustrates a battery discharge circuit 1000, according to oneembodiment. Under normal operation line 1004 is held at a low potentialand a current control device, such as a silicon controlled rectifier1002, is in the OFF state and the battery voltage V_(batt) is applied tothe electronics system 400 since no current flows from the anode “A” tothe cathode “C” of the silicon controlled rectifier 1002. When, a highpotential control signal “Discharge Battery” is applied by the mainprocessor 902 on line 1004, the gate “G” of the silicon controlledrectifier 1002 is held high by capacitor C₁ and the silicon controlledrectifier 1002 conducts current from the anode “A” to the “C.” Thedischarge current is limited by resistor R₄. In alternate embodiments,rather then using the silicon controlled rectifier 1002, the currentcontrol device may be implemented using one or more diodes, transistors(e.g., FET, bipolar, unipolar), relays (solid state orelectromechanical), optical isolators, optical couplers, among otherelectronic elements that can be configured to for an electronic switchto control the discharge of current from the battery 300.

FIG. 41 illustrates a RF amplifier section with an output sensing testcircuit and magnetic switch element, according to one embodiment. Aspreviously discussed, in one embodiment, the main processor 902 canverify the output current (I) and output voltage (V) sensing function byinjecting a corresponding first test current 1102 and second testcurrent 1104 into a dummy load 1114. The main processor 902 then readsback the corresponding output sense current (I OutSense 1) throughcurrent sense terminal 1120 and output sense current (I Out Sense 2)through voltage sense terminal 1122 from the dummy load 1114 anddetermines whether the medical instrument 100 can operate or fail insafe mode. In one embodiment, the test current and voltage are appliedto the dummy load via electronically controlled switches such as FETtransistors, solid state relay, two-pole relay, and the like. The mainprocessor 902 verifies the output sensing functions once per hour whenit is inactive and once prior to every firing. It will be appreciatedthat these periods may vary based on the particular implementation.

To verify the output sensing function, the main processor 902 disablesthe operation of the RF amplifier section 1112 by disabling the drivercircuit 1116. Once the RF amplifier section 1112 is disabled, the mainprocessor 902 outputs a first inject test current (Inject Test I) signaland a second inject test voltage (Inject Test V) signal to the outputsensing test circuit 1100. As a result a first test current 1102 isinjected into resistors that turn ON transistor T1 1106, which turns ONtransistor T2 1108 to generate I Out Sense 1 current through thetransistor T2 1108. The current I Out Sense 1 flows out of the currentsense terminal 1120 and is detected by the main processor 902 as the ISense signal. A second test current 1104 is applied through the inputsection of a solid state relay 1110 (SSR). This causes a current I OutSense 2 to flow through the dummy load 1114. The current I Out Sense 2flows out of the current sense terminal 1122 and is detected by the mainprocessor 902 as the V Sense signal. The dummy load 1114 load comprisesa first voltage divider network comprised of resistors R1-R4 and asecond voltage divider network comprised of R5-R8. As previouslydescribed, the main processor 902 reads the sensed voltage and currentsignals V Sense and I Sense to determine the operation of the voltage(V) and current (I) sensing function of the medical instrument 100.

In one embodiment, the magnetically actuated element 606, which works inconjunction with the magnet 602 located in the clip 600, 650. As shownin FIG. 41, in one embodiment, the magnetically operated element 606 maybe implemented as a reed switch 1118. The reed switch 1118 electricallydisconnects the battery power from the electronics system 400 while itis held in a first state by the magnetic flux generated by the magnet602. When the magnet 602 is removed and the magnetic flux does notinfluence the reed switch 1118, battery power is connected to theelectronics system 400 and the system undergoes an initializationalgorithm, as described hereinbelow.

Before the describing the initialization algorithm, several connectionoptions for the battery 300 are now described with reference to FIGS.42-47. As previously discussed, the electronics system 400 will not bepowered when undergoing sterilization, and will draw no current. In oneembodiment, the electronics system 400 is disabled by a magneticallyoperated element located in the clip 600, 650, one example of which isthe reed switch 1118 shown in FIG. 41, and the magnet 602 which isencased in the clip 600 and the tilted magnetic pocket 654 of the clip650. The clip 600, 650 is fitted to the medical instrument 100 as partof the manufacturing process, and must be removed to enable power fromthe battery 300. When powered, in the idle condition the load circuitdraws an average of about 10 mA, with peaks of up to about 65 mA. Whenthe activation button 114 is pressed, the device draws an average ofabout 5 A, with peaks of about 15.5 A from the battery 300. Whenpackaged, the jaws are closed and there is no material between them. Thevoltage generated across the jaws is about 85V rms. This arrangementmeans there are two methods for preventing the generation of highvoltages or currents—the magnetic clip 600, 650 is the primary disablingmechanism, and the activation button 114 is the second.

As previously discussed, certain sections of the hardware circuits maybe shut down or placed in sleep mode to conserve energy and thus extendthe life of the battery 300. In particular, amplifier circuitsassociated with the injection of the test current and test voltage andsensing the output sense currents may be placed in sleep mode orperiodically shut down to conserve energy.

FIG. 42 illustrates a fused battery connected to a substrate-mountedfield effect transistor (FET), according to one embodiment. In theembodiment shown in FIG. 42, a battery connection circuit 1200 comprisesthe battery 300, the magnet 602, the reed switch 1118, an FET 1202, tworesistors R1, R2 1204, 1206, and the electronics system 400. In thisimplementation, when the protective clip 600 is removed, the reed switch1118 closes, enabling current to flow through the control FET 1202, thuscoupling the electronics system 400 to the return (−) terminal of thebattery 300. Leakage current through the FET is approximately 1 uA. Thebattery is coupled to the (+) and (−) terminals via corresponding fuses1208, 1210.

FIG. 43 illustrates a fused battery connected to a substrate-mountedcontrol relay, according to one embodiment. In the embodiment shown inFIG. 43, a battery connection circuit 1300 comprises the battery 300,the magnet 602, the reed switch 1118, and a control relay 1302comprising a primary winding 1304 that controls a switch 1306. In thisimplementation, when the protective clip 600 is removed, the reed switch1118 closes, energizing the relay 1302 and connecting the electronicssystem 400 to the return (−) terminal of the battery 300. Leakagecurrent is zero, because the switch 1306 is physically open when theprimary winding 1304 in not energized. The operating current, however,to hold the relay 1304 open is approximately 5 mA, which could involveincreasing battery size.

FIG. 44 illustrates a potted fused battery connected to asubstrate-mounted FET, according to one embodiment. The connectioncircuit 1400 is similar to the connection circuit 1200 shown in FIG. 42,but with the top of the battery 300 potted in potting compound 1402.Thus, EtO sterilization gas will have no access to the individualbattery cells 300 a, 300 b, 300 c, and the first exposed contact is tothe fused contacts.

FIG. 45 illustrates a potted fused battery connected to asubstrate-mounted control relay, according to one embodiment. Theconnection circuit 1500 is similar to the connection circuit 1300 shownin FIG. 23, but with the top of the battery 300 potted in pottingcompound 1402. Thus, EtO sterilization gas will have no access to theindividual battery cells 300 a, 300 b, 300 c, and the first exposedcontact is to the fused contacts.

FIG. 46 illustrates a potted fused battery including a reed relay andcontrol FET, according to one embodiment. The connection circuit 1600 issimilar to the connection circuit 1400 shown in FIG. 24, but with reedrelay 1118 and the control FET 1202 included in the potting compound1402 as well as the top of the battery 300. Thus, EtO sterilization gaswill have no access to the individual battery cells 300 a, 300 b, 300 c,the reed relay 1118, and the control FET 1202, and the first exposedcontact is to the fused contacts.

FIG. 47 illustrates a potted fused battery including a reed relay andcontrol relay, according to one embodiment. The connection circuit 1700is similar to the connection circuit 1500 shown in FIG. 45, but withreed relay 1118 and the control relay 1302 included in the pottingcompound 1402 as well as the top of the battery 300. Thus, EtOsterilization gas will have no access to the individual battery cells300 a, 300 b, 300 c, the reed relay 1118, and the control relay 1302,and the first exposed contact is to the fused contacts.

Having described various systems associated with the medical instrument100, the description now turns to a user interface specification of themedical instrument 100, according to one embodiment. Accordingly, in oneembodiment, the medical instrument 100 comprises visual feedbackelements 118 a, 118 b. In one embodiment, the visual feedback elements118 a, 118 b each comprises RED, GREEN, BLUE (RGB) LEDs as shown in FIG.39.

The state of the medical instrument 100 can be determined by the stateof the visual feedback elements 118 a, 118 b as follows:

Solid Green: indicates that the medical instrument 100 is ready to beused, everything is functioning normally.

Flashing Green: indicates that medical instrument 100 is ready to beused, but there is only enough energy for a limited, e.g., low, numberof operations such as transections remaining (a minimum of 5transections are left when flashing first begins). In one embodiment,the rate of flashing is 300 ms on, 300 ms off, 300 ms on, 300 ms off.

Solid Blue: indicates that energy is being delivered to the medicalinstrument 100.

Solid Red: indicates a terminal failure and the medical instrument 100can no longer be used. Energy is not being delivered to the medicalinstrument 100. All Solid Red light conditions have a 4 second timeout;after which the LED goes OFF. Power cannot be activated when the LED isSolid Red—can only activate power when LED is Green or Flashing Green.

Flashing Red: indicates a fault that may be recoverable and to wait forthe light to change to Green or Red before operation can be resumed.Energy is not being delivered to the medical instrument 100 when the LEDis Flashing Red. The rate of flashing is 300 ms on, 300 ms off, 300 mson, 300 ms off. Power cannot be activated when the LED is FlashingRed—can only activate power when the LED Is Green or Flashing Green.

OFF: If before the plastic clip 600 has been removed, indicates thatdevice has not yet been powered ON by removing the clip 600. If any timeafter the clip 600 has been removed, indicates that device ispermanently powered OFF, and can be disposed of.

In one embodiment, the medical instrument 100 comprises an audiofeedback element 410. The state of the medical instrument 100 can bedetermined by the state of the audio feedback element 410 as follows:

Power ON Tone: indicates that the medical instrument 100 has beenpowered ON. This occurs when the plastic clip 600 is removed. The audiofeedback element 410 emits an audible 2.55 kHz 800 ms beep.

Activation Tone: indicates that energy is being delivered. This occurswhen the hand activation button 114 is pressed by the user. The audiofeedback element 410 emits an audible 2.55 kHz 150 ms beep, 200 mspause, 2.55 kHz 150 ms beep, 200 ms pause, an so on. The beeping patterncontinues as long as power is being activated and upper impedance limithas not been reached.

Activation Tone2: indicates that the upper impedance threshold has beenreached. This occurs when the hand activation button 114 is pressed byuser, and the upper impedance limit has been reached. The audio feedbackelement 410 emits an audible 2.8 kHz 150 ms beep, 200 ms pause, 2.8 kHz150 ms beep, 200 ms pause, and so on. The Tone2 beeping pattern latches.After it has been reached, it continues as long as power is beingactivated or until Cycle Complete.

Cycle Complete Tone: indicates that the activation cycle is complete.The audio feedback element 410 emits an audible 2.8 kHz 800 ms beep.

Alert Tone: indicates an alert. The LED visual feedback element 118 a,118 b provides further information. The audio feedback element 410 emitsan audible 2.9 kHz 250 ms beep, 50 ms pause, 2.55 kHz 350 ms beep, 200ms pause, 2.9 kHz 250 ms beep, 50 ms pause 2.55 kHz 350 ms beep, 200 mspause, 2.9 kHz 250 ms beep, 50 ms pause, 2.55 kHz 350 ms beep. Thetwo-tone beep repeats three times, then does not repeat after that).Power to the medical instrument 100 cannot be activated until “alert”sound has completed.

Timeout: indicates that activation cycle has timed out. Reactivate tocontinue. The audio feedback element 410 emits an audible 2.8 kHz 50 msbeep, 50 ms pause, 2.8 kHz 50 ms beep.

Solid Tone: indicates that the user disable button is being pressed. Theaudio feedback element 410 emits an audible continuous 2.55 kHz tonewhile being held, up to 4 seconds.

TABLE 3 below summarizes one embodiment of a user interface indicatingthe status (e.g., event/scenario) of the medical instrument 100 and thecorresponding visual and audible feedback provided by the userinterface.

TABLE 3 Device Status LED Feedback Audible Feedback Notes Power is OFFNo light None Turn power ON by Solid Green One long beep removing theIlluminates immediately when immediately when initialization Clip.initialization Clip is removed. initialization Clip is Indicates deviceis ready to be used, removed indicates everything functioning normally.power in ON. Power is ON but not Solid Green None being activated,Device ready to be used, everything device ready, above functioningnormally. the “low transections remaining” threshold. Power ON, deviceFlashing Green Two tone beeps: ready, power not Indicates that device isready to be Indicates an alert: being activated, used, but a low numberof look at LED below the “low transections remain; a minimum ofindicators for transections five transections are left when furtherinformation. remaining” flashing first begins. threshold. Power ON,device Solid Red Two tone beeps: ready, power not Indicates a terminalfailure, device Indicates an alert: being activated, “No can no longerbe used. Energy is look at LED transections not being delivered.indicators for remaining” further information. Activating power SolidBlue Continuous Feedback for Energy is being delivered. beeping duringactivation power is power activation. not affected by the Indicatesenergy is ‘low transections being delivered. remaining’ threshold-behaves the same whether above or below threshold Activation cycle SolidBlue until two short beep Two short beeps. Upon detection of timeoutoccurs after sound completes, then changes to Indicates that thetimeout, activation 25 sec of power Solid Green. Indicates device isactivation cycle beeping will be activation without ready to be used,everything has timed out. immediately reaching Cycle functioningnormally. Reactivate to interrupted. After Complete. continue. theinterruption of activation beeping there will be a 100 ms pause. Afterthe 100 ms pause, there will be the “Timeout” audio feedback. CycleComplete Solid Blue until Cycle Complete One long beep. Cycle completesound finishes, then changes to Indicates that sound should Solid Green.activation cycle is occur after the first complete. (200 ms) activationbeeping pause following system detection of cycle complete. ShortDetected Flashing Red, while in short circuit Two tone beeps. There willbe a mode. LED returns to Solid Green Indicates an alert: “five strikesand when short circuit mode is cleared, look at LED out” approach to orgoes to Solid Red if terminal indicators for this condition: if afailure. further information. short is detected Flashing Red indicates afault that on five may be recoverable: wait for LED to consecutivechange to Green or Red. activations, the Energy is not being detectedwhen fifth detection will LED is Flashing Red. result in a terminalsystem failure. Upon detection of short, the activation beeping will beimmediately interrupted. After the interruption of activation beepingthere will be a 100 ms pause. After the 100 ms pause, there will be the“Alert” audio feedback. Over-temperature Flashing Red, while in over-Two tone beeps. Upon detection of condition temperature condition.Indicates an alert: a temporary over- LED returns to Solid Green whenlook at LED temperature temperature drops below threshold. indicator forfurther condition during Flashing Red indicates a fault thatinformation. activation, may be recoverable: wait for LED to activation/change to Green or Red. beeping will not be Energy is not beingdelivered when interrupted. After LED is Flashing Red. the activation/beeping has been completed, there will be a 100 ms pause. After the 100ms pause, there will be the ‘Alert’ audio feedback. Terminal SystemSolid Red Two tone beeps. Upon detection of failure LED red light stayson for four Indicates an alert: terminal system seconds and then goesoff. look at LED failure, any Indicates a terminal failure, deviceindicator for further activation beeping can no longer be used.information. (if applicable) will Energy is not being delivered when beimmediately LED is Solid Red. interrupted. After the interruption of anyactivation beeping there will be a 100 ms pause. After the 100 ms pause,there will be the ‘Alert’ audio feedback. All Solid Red light conditionshave a 4 second timeout, after which the LED goes OFF User initiatesdevice While User Disable Button is Solid continuous disabling beforepressed and held continuously up to tone while disposal. Note: fourseconds, LED is Flashing Red. pressing and User can disable the Afterfour continuous seconds of holding User device by pressing User DisableButton being held, Disable Button and holding User LED goes to SolidRed. continuously up to Disable Button on NOTE: LED red light stays onfour four seconds. bottom of handle for seconds and then goes off. Afterfour four continuous Indicates a terminal failure, and continuousseconds. device can no longer be used. seconds of Energy is not beingdelivered. pressing User If User Disable Button is released at DisableButton, any time before four continuous sound changes to seconds havepassed, LED will two tone beeps. return to Solid Green or FlashingIndicates an alert: Green as appropriate. look at LED indicators forfurther information.

TABLE 4 below summarizes an additional or alternative embodiment of thestatus (e.g., event/scenario) of the medical instrument 100 and thecorresponding visual and audible feedback provided by the userinterface.

TABLE 4 Device Status LED Feedback Audible Feedback Notes Power is OFFNo light None Incomplete Cycle: Solid Blue, until activation button isNone user releases released, then Solid Green activation button prior tocycle complete and before the 15 second activation timeout. Power ON,ready, Flashing Green Alert Tone After the power not being appearance ofthe activated, below the Green Flashing Low Transections LED, there willbe Remaining 5 transections threshold. remaining. Ad If an activationends with a detection of an activation timeout, short detection, orover-temperature detection-and- the system has also crossed the low-usesremaining threshold after the same activation- then-the ‘Alert’ wouldsound once (as opposed to twice, or multiple times). In terms of alerthierarchy in this scenario in regard to the LED behavior, a shortdetection or over temperature takes precedence over the low-usesremaining indicator Once either the short or over- temperature conditionis cleared by the system, the LED would then go to Flashing Green toindicate the device is ready to be used, but there are a low number oftransections remaining. power ON, ready, Solid Red Alert Tone All SolidRed light power not being conditions have a activated, No 4 secondtimeout, Transections after which the Remaining. LED goes OFF. UserDisables Flashing Red while pressing & Solid Tone User can disableDevice before holding user disable button 120 Alert Tone the device bydisposal continuously up to 4 seconds. After pressing & holding fourcontinuous seconds of pressing the user disable user disable button, theLED goes to button on the Solid Red, then the LED goes OFF bottom of theafter 4 seconds timeout. If user handle for 4 releases user disablebutton at any continuous time before 4 continuous seconds, seconds. theLED will return to Solid Green The “Solid Tone” audio feedback is aSolid continuous tone that occurs as long as user presses & holds userdisable button, up to 4 seconds. If user releases user disable button atany time before 4 continuous seconds, sound goes off. At the end of 4seconds of continuous pressing, the “Solid Tone” slops, followed by a100 ms pause, followed by the “Alert” audio feedback. The “Alert” audiofeedback is accompanied by the LED changing to Solid Red, then LED goesOFF after 4 second timeout. Activating Power - Solid Blue ActivationTone2 Tone2 indicates Tone 2 that the upper impedance limit has beenreached during activation, and that the knife is ready to be fullyadvanced.

FIGS. 48A and 48B is a flow diagram of a process 1800 for initializingthe medical instrument 100 fitted with the initialization clip 600, 650,according to one embodiment. As shown in the process 1800, at 1802 themedical instrument 100 is programmed with an application code. Theapplication code is a set of computer instructions stored in thenonvolatile memory 402 that may be executed by the main processor 902,the safety processor 904, the controller 906, or any combinationthereof. The Production Test Complete flag is set to FALSE and theDevice Used flag also is set to FALSE.

The instrument 100 is then fitted with the clip 600, 650 and is turnedOFF at 1804 and the instrument 100 enters what is referred to as the“assembly state.” The Production Test Complete flag remains set to FALSEand the Device Used flag also remains set to FALSE.

At 1806 the instrument 100 is placed in the production mode after theclip 600, 650 is removed. In the production mode, the BLUE and GREENLEDs 118 a, b are turned ON and activation is inhibited. The ProductionTest Complete flag remains set to FALSE and the Device Used flag alsoremains set to FALSE. A timeout counter is started.

After a 1 second timeout, at 1808 the instrument 100 is still in theproduction mode, but remains idle. The user interface operates as pernormal mode. From the production mode 1808 the process can continue to1804 or to 1810. If the clip 600, 650 is fitted on the instrument 100prior to a ten minute timeout, the process 1800 returns to 1804 were theinstrument 100 is turned OFF and is placed in the assembly state. Aftera ten minute timeout period, the process 1800 continues at 1810. Theinstrument 100 is still in the production mode, but in a low powerconsumption state. The BLUE and GREEN LEDs 118 a, b are intermittentlyON (0.1 s ON and 1.9 s OFF). The clip 600, 650 is fitted back on theinstrument 100, which turns the instrument 100 OFF, and the process 1800returns to 1804. If at 1808 the instrument 100 is activated before theclip 600 is restored or before the ten-minute timeout period, theprocess continues to test mode at 1812. The Production Test Completeflag remains set to FALSE and the Device Used flag also remains set toFALSE. In test mode activations may be limited to four and timeout maybe set to ten minutes. Furthermore, upon entry to test mode, the GREENand BLUE LEDs 118 a, b are illuminated for 1 s. Subsequently, the LEDs118 a, b and the audio feedback element 410 follow the user interfacespecification.

At 1812, the instrument 100 is placed in test mode where the RFamplifier subsection 800 is turned ON. The user interface operates pernormal mode. The Production Test Complete flag is set to TRUE and theDevice Used flag remains set to FALSE.

From 1812, the clip 600, 650 may be fitted to the instrument 100 turningthe instrument 100 OFF and the process 1800 may continue at 1818 wherethe instrument 100 is placed in a shipping state. The Production TestComplete flag remains set to TRUE and the Device Used flag remains setto FALSE.

From 1812, the process may continue at 1814 after the instrument 100 isde-activated for the first three times. At 1814 the instrument 100 isplaced in idle mode. The UI operates as pre normal. The Production TestComplete flag remains set to TRUE and the Device Used flag remains setto FALSE. The instrument 100 is activated once more and the process 1800continues to 1812. The instrument 100 is de-activated a fourth time, theclip 600, 650 is fitted to the instrument 100, and the process 1800continues to 1816 where the instrument 100 is placed in low power modeand the BLUE and GREEN LEDs 118 a, b are flashed intermittently ON (0.1s ON and 1.9 s OFF). The Production Test Complete flag remains set toTRUE and the Device Used flag remains set to FALSE. The clip 600, 650 isfitted back on the instrument 100, which is turned OFF and placed in theshipping state. The instrument 100 enters low power mode after theinstrument 100 has been activated twice by pressing the activationbutton 114 or following expiration of the 10 minute timeout period.

From 1814, rather than activating the instrument 100, a 10 minutetimeout period may be allowed to lapse or the clip 600, 650 may befitted back on the instrument 100. If the 10 minute timeout period isallowed to lapse, the process 1800 continues 1816. If the clip 600, 650is fitted back on the instrument, the process 1800 continues at 1818.

From 1818, the instrument 100 may be shipped to the user. Before usingthe instrument 100, the user has to remove the clip 600, 650 from theinstrument 100 and then must activate the instrument 100. After the clip600, 650 is removed from the instrument 100 but before the activationbutton 114 is pressed, the process continues at 1820 where theinstrument is placed in normal mode but is in idle. The Production TestComplete flag remains set to TRUE and the Device Used flag remains setto FALSE. If the clip 600, 650 is fitted back on the instrument 100, theprocess 1800 continues back to 1818. If the activation button 114 isactivated, however, the process 1800 continues 1822 where the instrumentis placed in normal mode and the RF section is turned ON. Now ProductionTest Complete flag remains set to TRUE and the Device Used flag is setto TRUE. The instrument 100 only gets marked for disposal (Device UsedFlag is TRUE) if the instrument 100 has been activated and the limitswitch is pressed during normal mode. If the instrument 100 is nowde-activated, the process 1800 continues to 1824 where the instrument isplaced in normal mode idle. From 1824, if the instrument is activated bypressing the activation button 114, the process 1800 continues at 1822.From either 1822 or 1824, if the clip 600, 650 is fitted back on theinstrument 100, the process continues to 1826 where the instrument 100is turned OFF and enters an end of use state. Both the Production TestComplete flag and the Device Used flag remain set to TRUE. The clip 600,650 should be removed at the end of test as a final check to ensure theGREEN LED 118 a, b comes on. If the RED LED 118 a, b comes on instead,the instrument 100 has entered self destruct mode.

From 1826, if the clip 600, 650 is removed, the instrument 100 initiatesdischarging the battery 300 and the process 1800 continues to 1828 wherethe battery 300 continues discharging until the battery 300 is fullydischarged at 1830. From 1828, the clip 600, 650 may be fitted back onthe instrument 100, in which case, the process 1800 continues to 1826.If any fatal hardware errors occur from any instrument state such as,five short circuits, battery end of life, 8/10 hour timeout, disposalswitch 120 is pressed for more than 4 seconds, or the battery 300initiates discharge, the process 1800 continues to 1828.

FIG. 49-57 illustrates the ornamental design for a surgical instrumenthandle assembly as shown and described, according to one embedment.

FIG. 49 is a left perspective view of a handle assembly for a surgicalinstrument.

FIG. 50 is a right perspective view thereof.

FIG. 51 is a left perspective view thereof.

FIG. 52 is a left view thereof.

FIG. 53 is a front view thereof.

FIG. 54 is a right view thereof.

FIG. 55 is a rear view thereof.

FIG. 56 is a top view thereof.

FIG. 57 is a bottom view thereof.

It is worthy to note that any reference to “one aspect” or “an aspect”means that a particular feature, structure, or characteristic describedin connection with the aspect is included in at least one aspect. Thus,appearances of the phrases “in one aspect” or “in an aspect” in variousplaces throughout the specification are not necessarily all referring tothe same aspect. Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner in one or moreaspects.

Some aspects may be described using the expression “coupled” and“connected” along with their derivatives. It should be understood thatthese terms are not intended as synonyms for each other. For example,some aspects may be described using the term “connected” to indicatethat two or more elements are in direct physical or electrical contactwith each other. In another example, some aspects may be described usingthe term “coupled” to indicate that two or more elements are in directphysical or electrical contact. The term “coupled,” however, also maymean that two or more elements are not in direct contact with eachother, but yet still co-operate or interact with each other.

While certain features of the aspects have been illustrated as describedherein, many modifications, substitutions, changes and equivalents willnow occur to those skilled in the art. It is therefore to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true scope of the disclosed embodiments.

Various aspects of the subject matter described herein are set out inthe following numbered clauses:

1. A medical instrument comprising: a handle for gripping by a user, anend effector coupled to the handle and having at least one electricalcontact; a radio frequency (RF) generation circuit coupled to the handleand operable to generate an RF drive signal and to provide the RF drivesignal to the at least one electrical contact; wherein the RF generationcircuit comprises a parallel resonant circuit.

2. The medical instrument according to clause 1, wherein the RFgeneration circuit comprises switching circuitry that generates acyclically varying signal, such as a square wave signal, from a directcurrent (DC) supply and wherein the resonant circuit is configured toreceive the cyclically varying signal and wherein the cyclically varyingsignal is duty cycle modulated.

3. The medical instrument according to clause 1, comprising a batterycompartment for holding one or more batteries for providing power to theRF generation circuit for generating said RF drive signal.

4. The medical instrument according to clause 3, wherein the batterycompartment is configured to hold a module comprising the one or morebatteries and the RF generation circuit.

5. A device according to clause 1, further comprising: battery terminalsfor connecting to one or more batteries; wherein the RF generationcircuit is coupled to the battery terminals; wherein the frequencygeneration circuit comprises: switching circuitry for generating acyclically varying signal from a potential difference across the batteryterminals; and the resonant circuit, being a resonant drive circuitcoupled to the switching circuitry and operable to filter the cyclicallyvarying signal generated by the switching circuitry; and wherein the RFdrive signal is controlled by an output from said resonant drivecircuit.

6. The medical instrument according to clause 1, comprising a controlcircuit configured to vary the frequency of the RF drive signal.

7. The medical instrument according to clause 1, comprising a controlcircuit configured to vary the amplitude of the RF drive signal.

8. The medical instrument according to clause 1, comprising a controlcircuit configured to vary the duty cycle of the RF drive signal.

9. The medical instrument according to clause 8, wherein the controlcircuit is operable to receive a measurement of the RF drive signal andis operable to vary the frequency of the of the RF drive signal tocontrol the power, voltage and/or current delivered to the at least oneelectrical contact of the end effector.

10. The medical instrument according to clause 9, wherein themeasurement is obtained from a sampling circuit that samples a sensedvoltage or current signal at a sampling frequency that varies insynchronism with the frequency and phase of the RF drive signal.

11. The medical instrument according to clause 10, wherein the frequencyat which the sampling circuit is operable to sample the sensed signal isan integer fraction of the frequency of the RF drive signal.

12. The medical instrument according to clause 8, wherein the controlcircuit is configured to vary the frequency of the RF drive signalaround the resonant frequency of the resonant circuit.

13. The medical instrument according to clause 12, wherein the resonantcharacteristic of the resonant circuit varies with a load connected tothe at least one electrical contact and wherein the control circuit isconfigured to vary the RF drive frequency to track changes in theresonant characteristic of the resonant circuit.

14. The medical instrument according to clause 1, wherein the handlecomprises: a control lever to operate the end effector; and anactivation button to operate the RF generation circuit and deliver RFenergy to the end effector.

15. The medical instrument according to clause 14, comprising a rotationknob coupled to end effector to rotate the end effector about an anglegreater than 360°.

16. The medical instrument according to clause 14, comprising at leastone visual feedback element to indicate a state of the medicalinstrument.

17. The medical instrument according to clause 14, comprising an audiofeedback element to indicate a state of the medical instrument.

18. The medical instrument according to clause 17, comprising anaperture formed in the handle to provide a path for audio waves toescape an interior portion of the handle.

19. The medical device according to clause 14, comprising a knifelockout mechanism.

20. The medical device according to clause 14, comprising a clip coupledto the control lever.

21. The medical instrument according to clause 20, comprising a magnetlocated within the clip.

22. The medical instrument according to clause 21, comprising amagnetically operated element coupled to an electronics system of themedical instrument and a battery of the medical instrument, wherein whenthe magnet is located within the clip and the clip is coupled to thecontrol lever, the magnetically operated element disconnects the batteryfrom the system electronics.

1. A medical instrument comprising: a housing and a handle for grippingby a user, an end effector coupled to the handle and having at least oneelectrical contact; a battery; a radio frequency (RF) generation circuitcoupled to and operated by the battery and operable to generate an RFdrive signal and to provide the RF drive signal to the at least oneelectrical contact, wherein the RF generation circuit is supported bythe housing; wherein the RF generation circuit comprises a resonantcircuit comprising at least one inductive element constructed of litzwire.
 2. The medical instrument of claim 1, wherein the resonant circuitcomprises a transformer and an inductor, wherein the transformercomprises a primary coil and a secondary coil constructed of litz wire.3. The medical instrument of claim 2, wherein the primary coil isconstructed of 300 strand 46 gauge litz wire wound at 24 turns per foot(TPF).
 4. The medical instrument of claim 3, wherein the primary coilhas an inductance of about 270 nH, an AC resistance of less than 46 mΩ,and a DC resistance less than or equal to 5 mΩ.
 5. The medicalinstrument of claim 2, wherein the secondary coil is constructed of 105strand 44 gauge litz wire wound at 24 TPF.
 6. The medical instrument ofclaim 5, wherein the secondary coil has an inductance of about 22 pH at430 kHz, an AC resistance of less than 2.5Ω, and a DC resistance lessthan or equal to 80 mΩ.
 7. The medical instrument of claim 2, whereinthe inductor comprises a coil constructed of litz wire.
 8. The medicalinstrument of claim 7, wherein the inductor coil is constructed of 300strand 46 gauge litz wire wound at 24 turns per foot (TPF).
 9. Themedical instrument of claim 8, wherein the inductor coil has aninductance of about 345 nH at 430 kHz, an AC resistance of less than 50mΩ, and a DC resistance less than or equal to 7 mΩ.
 10. The medicalinstrument of claim 2, wherein the transformer comprises a ferrite core.11. The medical instrument of claim 2, wherein the inductor comprises aferrite core.
 12. The medical instrument of claim 2, wherein theinductor and the primary coil of the transformer form a resonantcircuit.
 13. A medical instrument comprising: a battery operated radiofrequency (RF) generation circuit operable to generate an RF drivesignal and to provide the RF drive signal to the at least one electricalcontact, wherein the RF generation circuit comprises a resonant circuitcomprising at least one inductive element constructed of litz wire. 14.The medical instrument according to claim 13, wherein the RF generationcircuit comprises switching circuitry that generates a cyclicallyvarying signal, such as a square wave signal, from a direct current (DC)supply and wherein the resonant circuit is configured to receive thecyclically varying signal and wherein the cyclically varying signal isduty cycle modulated.
 15. The medical instrument according to claim 13,comprising a battery compartment for holding one or more batteries forproviding power to the RF generation circuit for generating said RFdrive signal.
 16. The medical instrument according to claim 13, furthercomprising: battery terminals for connecting to one or more batteries;wherein the RF generation circuit is coupled to the battery terminals;wherein the frequency generation circuit comprises: switching circuitryfor generating a cyclically varying signal from a potential differenceacross the battery terminals; and the resonant circuit, being a resonantdrive circuit coupled to the switching circuitry and operable to filterthe cyclically varying signal generated by the switching circuitry; andwherein the RF drive signal is controlled by an output from saidresonant drive circuit.
 17. The medical instrument according to 13,comprising a control circuit configured to vary the frequency of the RFdrive signal.
 18. The medical instrument according to 13, comprising acontrol circuit configured to vary the amplitude of the RF drive signal.19. The medical instrument of claim 13, wherein the resonant circuitcomprises a transformer and an inductor, wherein the transformercomprises a primary coil and a secondary coil constructed of litz wire.20. A medical instrument comprising: a battery operated radio frequency(RF) generation circuit operable to generate an RF drive signal and toprovide the RF drive signal to the at least one electrical contact; anda control circuit configured to vary the duty cycle of the RF drivesignal; wherein the RF generation circuit comprises a resonant circuitcomprising at least one inductive element constructed of litz wire. 21.The medical instrument according to claim 20, wherein the controlcircuit is operable to receive a measurement of the RF drive signal andis operable to vary the frequency of the of the RF drive signal tocontrol the power, voltage and/or current delivered to the at least oneelectrical contact of the end effector.
 22. The medical instrumentaccording to claim 21, wherein the measurement is obtained from asampling circuit that samples a sensed voltage or current signal at asampling frequency that varies in synchronism with the frequency andphase of the RF drive signal.
 23. The medical instrument according toclaim 22, wherein the frequency at which the sampling circuit isoperable to sample the sensed signal is an integer fraction of thefrequency of the RF drive signal.
 24. The medical instrument accordingto claim 20, wherein the control circuit is configured to vary thefrequency of the RF drive signal around the resonant frequency of theresonant circuit.
 25. The medical instrument according to claim 24,wherein the resonant characteristic of the resonant circuit varies witha load connected to the at least one electrical contact and wherein thecontrol circuit is configured to vary the RF drive frequency to trackchanges in the resonant characteristic of the resonant circuit.